CHICLES  OF  THE  AIR 


A  POPULAR  EXPOSITION  OF 
MODERN  AERONAUTIC  S 
WITH  WORKING  DRAWINGS 


VICTOR  LOUGHEED 


Tjibrarv 


Vehicles  of  the  Air 


VEHICLES  OF  THE  AIR 

A  Popular  Exposition  of  Modern  Aeronautics 
With  Working  Drawings 


By 

VICTOR  LOUGHEED 

i* 

Member  of  the  Aeronautic  Society,  Founder  Member  of  the  Society  of  Auto- 
mobile Engineers,  Secretary  of  the  American  Aeronautical  Association. 
Consulting  Engineer  of  the  Aero  Club  of  Illinois,  former 
editor  of  Motor,  and  author  of  "  Some  Trends 
of  Modern  Automobile  Design." 


PUBLISHERS  ;      .:; 

THE    REILLY    AND    BRITTON    CO. 

CHICAGO 


Engineering 
Library 

VEHICLES   OP  THE   AIR 

SECOND  EDITION— REVISED  AND  ENLARGED 


Entered  at  Stationers'  Hall 

Copyright,  1909.  by  The  Rellly  and  Brltton  Co. 

Copyright,  1910,  by  The  Rellly  and  Brltton  Co. 

AH  Rights  Reserved 


PHOTOGRAPHS  BY 

M.  Branger,  E.  FlHatre,  M.  Rol.  and  J.  Theodoresco,  of  Paris.    All  illustrations 

herein  are  fully  protected  by  International  copyright.    Reproductions 

positively  will  not  be  permitted  without  due  credit,  and 

written  authorization  from  the  publishers. 


TABLE  OF  CONTENTS 

INTRODUCTION 

Scope  and  Prophecy 21 

Skepticism   is   Ignorance 23 

Three   Traversable  Media 24 

Types  of  Air  Craft 24 

Aeroplane  Most  Successful 26 

Speed   and   Radius 27 

Sizes  of  Aeroplanes 28 

First  and  Operating  Costs 28 

The   Moral   Aspect 29 

The  Physical  Hazard 29 

Dangers  in  All  Travel 32 

Fear  a  Habit  of  Mind 33 

Commercial   Applications 34 

Limitations   Expected 35 

Relation  to  Warfare 36 

An   Imaginative    Spectacle 37 

Travel  Over  Water 38 

Conclusion 39 

CHAPTER  1— THE  ATMOSPHERE. 

Introduction    43 

EXTENT 43 

PROPERTIES  AND  CHARACTERISTICS 45 

Weight    45 

Composition  46 

Color  and  Transparence 49 

AIR  AT  REST 48 

Compressibility   49 

Effect    of    Temperature 49 

Liquefaction  and  Solidification 50 

AIR   IN   MOTION 50 

Inertia    51 

Elasticity   52 

Viscosity    53 

METEOROLOGY 53 

Temperature 54 

Barometric  Pressure 56 

Humidity 56 

Condensation  of  Moisture , 57 

Winds 57 

Coastal  Winds 59 

Trade   Winds 60 

Cyclones,  Whirlwinds,  and  Tornados 61 

Ascending  Components 62 

Wind   Velocities 62 

Atmospheric  Electricity 64 

7 


804557 


8  VEHICLES  OF  THE  AIR 

CHAPTER  2— LIGHTER-THAN-AIR  MACHINES. 

Introductory    65 

NON-DIRIGIBLE  BALLOONS 66 

History 66 

Spherical  Types 75 

DIRIGIBLE  BALLOONS 76 

History 80 

Spherical  Types 88 

Elongated  Types r 89 

Pointed  Ends 89 

Rounded    Ends 90 

Sectional    Construction 90 

The  Effect  of  Size 90 

Envelope   Materials 91 

Sheet  Metal 92 

Silk   93 

Cotton 93 

Linen    94 

Miscellaneous  Envelope  Materials 94 

Coating    Materials 95 

Inflation    96 

Heated  Air    97 

Hydrogen  98 

Illuminating    Gases 101 

Vacuum    ; 101 

Miscellaneous    102 

Nettings  103 

Car  Construction   104 

Rattans    105 

Wood    106 

Miscellaneous 106 

Height    Control 106 

Non-Lifting    Balloons 107 

Escape    Valves 107 

Ballast    109 

Compressed   Gas 109 

Drag    Ropes 110 

Open    Necks 110 

Internal    Balloons Ill 

Moisture     , 112 

Temperature    112 

Steering  113 

Lateral  Steering  113 

Vertical  Steering 114 

Balloon  Housing 115 

Sheds  115 

Landing  Pits 116 

CHAPTER  3— HEAVIER-THAN-AIR  MACHINES. 

Introductory 117 

ORNITHOPTERS     118 

History     118 

Two   Chief    Classes 124 

"Recent  Ornithopters 124 

Analogies   in   Nature 124 

HELICOPTERS    125 

History 126 


CONTENTS  9 

Recent  Experiments 129 

Lateral    Progression 130 

Analogy    With  Aeroplane .131 

AEBOPLANES 131 

AEEOPLANE  HISTOEY 132 

Clement  Ader 134 

Louis  Bleriot ..135 

Octave  Chanute    136 

Samuel  Pierpont  Langley. . 136 

Otto  and  Gustav  Lihemhal 137 

John  J.  Montgomery 138 

A.    Penaud 146 

Percy    S.    Pilcher 147 

Alberto    Santos-Dumont 148 

F.   H.    Wenham 149 

Wilbur  and  Orville  Wright 149 

Voisin  Brothers 153 

Miscellaneous    153 

CHAPTER  4— AEEOPLANE  DETAILS. 

Introductory 158 

ANALOGIES  IN  NATUBE 159 

Flying    Fish 161 

Comparison  of  Flying  Animals  and  Aeroplanes 162 

Flying  Lizards 163 

Flying    Squirrels 163 

Flying    Lemur 163 

Flying   Frog 164 

Soaring    Birds 164 

Soaring    Bats 165 

The  Pterodactyl 165 

Flying    Insects 166 

MONOPLANES  167 

MULTIPLANES    168 

Biplanes    169 

More  Than  Two  Surfaces , 169 

FOEMS  OF  SUEFACES 169 

Flat    Sections 171 

Curved  Sections 172 

Arcs  of  Circles 172 

Parabolic  Surfaces   173 

Force  and  Motion 193 

Momentum     194 

Action  and  Beaction 194 

Impact  of  Elaitic  Bodies 195 

The  Impact  of  Fluids 198 

Application 199 

Flattened  Tips 203 

Angles  of  Chords 204 

Wing    Outlines 204 

Length  and  Breadth 204 

ABBANGEMENTS  OF  SUBFACES 205 

Advancing  and  Following  Surfaces 205 

Superposed  Surfaces , 205 

Staggered    Surfaces 205 

Lateral   Placings 206 

Separated  Wings 206 


10  VEHICLES  OF  THE  AIR 

Lateral  Curvature 207 

Dihedral  Angles 207 

VERTICAL  SURFACES 209 

SUSTENTION  OF  SURFACES 210 

Effect  of  Section 210 

Effect  of  Angle 211 

Effect   of  Speed 211 

Effect  of  Outline 212 

Effect  of  Adjacent  Surfaces 212 

Center  of  Pressure 213 

Head   Eesistances 213 

METHODS  OF  BALANCING 215 

Lateral    Balance 215 

Vertical    Surfaces 216 

Dihedral   Angles 216 

Wing  Warping 216 

Tilting  Wing  Tips 217 

Hinged  Wing  Tips 217 

Variable  Wing  Areas. . . : 218 

Shifting  Weight 218 

Rocking   Wings    218 

Swinging  Wings  or  Wing  Tips 219 

Plural  Wing  Tips 220 

Longitudinal  Balance 220 

By  Front  Rudders 220 

By  Rear  Rudders 220 

Box  Tails 220 

Shifting  Weights 221 

Elevators  as  Carrying  Surfaces 221 

Automatic  Equilibrium  221 

Arrangement  of  Surfaces 222 

Electric  Devices 222 

The   Gyroscope 222 

Compressed  Air 223 

The   Pendulum 223 

STEERING 223 

Effects  of  Balancing 223 

Vertical   Sudders 224 

Pivoted  Rudders 224 

Flexible   Rudders 224 

Horizontal  Eudders 225 

Twisting  Eudders 225 

CONTROLLING  MEANS 226 

Compound  Movements 227 

Plural   Operators 227 

Wheels 228 

Levers    228 

Pedals 229 

Miscellaneous    229 

Shoulder  Forks 229 

Body    Cradles 229 

FRAMING 230 

CHAPTER  5— PROPULSION. 

Introductory   231 

MISCELLANEOUS  PROPELLING  DEVICES 231 

Feathering  Paddles 

Wave  Surfaces 233 


CONTENTS  11 

Reciprocating  Wings  and  Oars 234 

SCREW    PROPELLERS 236 

Some  Comparisons 237 

Essential  Characteristics 238 

Effective  Surface 241 

Angles  of  Blades 242 

Slip   244 

Forms  of  Surfaces 244 

Plane   Sections 245 

Parabolic  Sections 245 

Blade  Outlines 246 

Multilladed   Propellers 248 

Two-Bladed  Propellers 249 

Propeller  Diameters 250 

Arrangements  of  Blades 252 

Right-Angled  Propeller  Blades 252 

Dihedrally-Aranged  Propeller  Blades 253 

Propeller  Efficiencies  253 

The  Effects  of  Form 255 

The  Effects  of  Rotational  Speed 255 

The  Effects  of  Vehicle  Speed 256 

The  Effects  of  Skin  Friction 257 

Propeller   Placings 258 

Single  Propellers 259 

Plural  Propellers 259 

Location  of  Propeller  Thrust 264 

Propeller  Materials 264 

Wood    265 

Steel   268 

Aluminum  Alloys 268 

Framing   and   Fabric 269 

Propeller  Hubs 269 

A  TYPICAL  PROPELLER 270 

CHAPTER  6— POWEE  PLANTS. 

Introductory  273 

GASOLINE  ENGINES  277 

Multicylinder  Designs 277 

Clylinder  Arrangements 279 

Vertical  Cylinders 279 

V-Shaped  Engines 280 

Opposed  Cylinders 281 

Revolving  Cylinders 282 

Miscellaneous  Arrangements 284 

Ignition  284 

Make-and  Break  Ignition 284 

Jump-Spark  Ignition 285 

Hot-Tube  Ignition 287 

Ignition  by  Heat  of  Compression 287 

Catalytic  Ignition 288 

Cooling  288 

Water  Cooling 289 

Air  Cooling 290 

Carburetion  291 

Carburetors  291 

Fuel  Pumps 294 


12  VEHICLES  OF  THE  AIR 

Muffling  296 

Auxiliary  Exhausts 297 

Flywheels 297 

STEAM  ENGINES 299 

Available  Types  301 

Boilers  301 

Burners  303 

Fuels 303 

Comparison  of  Fuels 304 

ELECTRICITY  7 . .  304 

Electric  Motors 304 

Current  Sources 305 

Storage  Batteries 306 

Primary  Batteries 307 

Thermopiles  307 

MISCELLANEOUS  308 

Compressed  Air  309 

Carbonic  Acid 309 

Vapor  Motors 309 

Spring  Motors 310 

Socket  Schemes 310 

TANKS   310 

CHAPTEE  7— TRANSMISSION  ELEMENTS. 

Introductory    313 

CHAINS  AND  SPEOCKETS 314 

Block    Chains 316 

Roller  Chains   317 

Miscellaneous 317 

Block  Chains 317 

Standard  American  Roller  Chains 318 

Roller    Chains 318 

Cable  Chains 319 

Eeversible  Sprockets 319 

Missed  Teeth 319 

SHAFTS  AND   GEARS 320 

Shafts    320 

Spur   Gears 321 

Bevel  Gears 322 

Staggered  and  Herringbone  Teeth 323 

BELTS  AND  PULLEYS 324 

Pulley    Construction 324 

Belt    Materials 325 

CLUTCHES    325 

CHAPTER  8— BEARINGS. 

Introductory 327 

BALL  BEARINGS 328 

Adjustable  Ball  Bearings 328 

Annular  Ball  Bearings 330 

Annular  Ball-Bearing  Sizes,  Capacities,  and  Weights 337 

ROLLER  BEARINGS 339 

Cylindrical  Eoller  Bearings 340 

Flexible  Eoller  Bearings 340 

Tapered  Eoller  Bearings 341 

PLAIN  BEARINGS 342 

Plain  Bearing  Materials 342 

Steel    .             342 


CONTENTS  13 

Cast  Iron 343 

Bronzes    343 

Brasses  343 

Babbitt 343 

Graphite   344 

Wood 344 

Vulcanized  Fiber 344 

Finish  of  Plain  Bearings 344 

Areas 344 

Scraping 345 

MISCELLANEOUS  BEARINGS 346 

CHAPTER  9— LUBRICATION. 

Introductory    347 

SPLASH  LUBRICATION 347 

King  and  Chain  Oilers 348 

GRAVITY  LUBRICATION 349 

Oil    Cups 349 

Reservoir  Systems 350 

FORCED    LUBRICATION 350 

Pressure  Feed 350 

Single  Pumps 351 

Multiple  Pumps 351 

Grease    Cups 352 

LUBRICANTS     352 

Mineral   Oils 352 

Vaseline   353 

Vegetable  Oils 353 

Castor   Oil 353 

Olive   Oil 353 

Animal    Oils 354 

Sperm    Oil 354 

Tallow    354 

Miscellaneous  Lubricants 354 

Water   354 

Kerosene    355 

CHAPTER    10— STARTING    AND    ALIGHTING. 

Introductory   356 

STARTING  DEVICES 357 

Wheels    358 

Rails     358 

Floats 359 

Runners    360 

The  Starting  Impulse  360 

Propeller  Thrust 361 

Dropped  Weights 362 

Winding  Drums 363 

Inclined  Surfaces 364 

Launching  Vehicles 365 

Automobiles 365 

Railway  Cars 365 

Boats 366 

Cleared  Areas 366 

Facing  the  Wind 367 

Launching  from  Height 368 

ALIGHTING  GEARS 369 

Wheels .  369 


14  VEHICLES  OF  THE  AIR 

Bunners 370 

Floats   370 

Miscellaneous 371 

CHAPTEE  11— MATERIALS  AND  CONSTRUCTION. 

Introductory    372 

WOODS   373 

Hardwoods    374 

Applewood  375 

Ash    375 

Bamboo  375 

Birch    376 

Boxwood    376 

Elm  376 

Hemlock  377 

Hickory  377 

Holly    378 

Mahogany 378 

Maple    378 

Oak 378 

Walnut  378 

Softwoods 379 

Pines 379 

Poplar    379 

Spruce  379 

Willow 380 

Veneers  and  Bendings 380 

METALS    381 

Iron   382 

Steel    382 

Alloy  Steels 383 

Cast  Iron 384 

Aluminum  Alloys 384 

Aerial  Metal 384 

Aluman 384 

Argentalium   385 

Chromaluminum 385 

Magnalium    385 

Nickel- Aluminum 385 

Partinium 385 

Wolframinium    385 

Brasses  and  Bronzes 386 

Aluminum  Bronze 386 

Phosphor  Bronze 386 

Metal  Parts 386 

COBDAGE  AND  TEXTILES 387 

Cotton 388 

Linen 388 

Silk   388 

PAINTS  AND  VARNISHES 388 

Oils   388 

Shellacs   389 

Spar   Varnishes 389 

Aluminum  Paint 389 

Miscellaneous   389 

MISCELLANEOUS    , 389 

Catgut   389 

China  Grass 390 

Hair  390 

Bawhide 390 


CONTENTS  15 

Silk  Cord 390 

Silkworm  Gut 390 

ASSEMBLING  MATERIALS  AND  METHODS 390 

Nails 390 

Glues  and  Cements 390 

Screws   ...391 

Bolts  391 

Clips   391 

Eivets   391 

Electric  Welding 391 

Autogenous    Welding 391 

Brazing   391 

Soldering 392 

Tabular  Comparisons  of  Materials 392 

Metals 393 

Miscellaneous  Materials 393 

Transverse  Strength  of  Wood  Bars 393 

Woods 393 

CHAPTBE  12— TYPICAL  AEROPLANES. 

Introductory 394 

Antoinette  Monoplanes 396 

Bleriot  Monoplanes 396 

Chanute  Gliders 398 

Cody  Biplane 399 

Curtiss  Biplane 400 

Farman  Biplane 404 

Langley  Machine 404 

Lilienthal  's  Machines 404 

Maxim  Multiplane 405 

Montgomery  Machine 406 

Pilcher  Gliders 407 

E.  E.  P.  Monoplanes 408 

Santos-Dumont  Monoplane 408 

Voisin  Biplane 409 

Wright  Biplane 409 

CHAPTER  13— ACCESSORIES. 

Introductory 410 

LIGHTING  SYSTEMS 410 

Electric  Lighting 411 

Advantages  of  Uniform  Motor  Speed 411 

Arc  Lamps 411 

Incandescent  Lamps 412 

The  Nernest  Lamp 413 

Acetylene  413 

Storage  Tanks 414 

Acetylene  Generators 414 

Acetylene  Burners 415 

Oxygen  Systems 416 

With  Hydrogen 416 

With  Gasoline. 416 

With  Acetylene 416 

Incandescent  Mantles 416 

With  Gas 417 

With  Liquid  Fuels 417 

Oil  Lamps 417 

Sperm  Oil 417 

Kerosene  418 


16  VEHICLES  OF  THE  AIR 

Reflectors 413 

Arrangement  of  Lights 419 

SPEED  AND  DISTANCE  MEASUREMENTS 420 

Anemometers  420 

Miscellaneous  .  421 

COMPASS 422 

Fixed-Dial  Compasses 423 

Floating-Dial  Compasses 423 

BAROMETERS 424 

Mercurial  Barometers 424 

Aneroid  Barometers 424 

WIND  VANES 425 

MISCELLANEOUS  INSTRUMENTS 425 

CHAPTER  14— MISCELLANY. 

Introductory .  427 

APPLICATIONS    428 

Warfare  429 

Sport , 432 

Mail  and  Express '. 433 

News  Service 434 

Effects  of  Low  Cost  and  Maintenance 434 

General  Effects 435 

RADII  OF  ACTION 436 

Influence  of  Wind 437 

DEMOUNTABILITY 437 

PASSENGER  ACCOMMODATION 439 

Seats 440 

Housing  ....  * 440 

Upholstery  440 

Pneumatic  Cushions 440 

Heating 441 

By  the  Exhaust 441 

PARACHUTES 442 

DESIGNING   443 

TESTING  AND  LEARNING 444 

Learning  from  Teacher. 444 

Practice  Close  to  the  Surface 444 

Practice  over  Water 445 

Maintaining  Headway 445 

Landing 445 

AERIAL  NAVIGATION. 446 

Flying  High 446 

Steadier  Air 446 

Choice  of  Landing 447 

Flying  Low 447 

Falling 448 

Striking  Obstacles 448 

Vortices  and  Currents 448 

TERRESTRIAL  ADJUNCTS 449 

Signals 449 

Fog  Horns  and  Whistles 450 

PATENTS   451 

GLOSSARY  OF  AERONAUTICAL  TERMS 464 

CHAPTER  15— FLIGHT  RECORDS. 

Introductory 473 

TABULAR  HISTORY  OF  FLIGHTS 480 

INDEX 

Commences  on  Page 492 


LIST  OP  ILLUSTRATIONS 

FIGURE.  PAGE. 

Sands,  in  an  Antoinette  Monoplane,  Coming  to  Ground  at 

Cannes,   France    Frontispiece 

Count  de  Lambert  in  Wright  biplane  at  Juvisy,  France 452 

1. — Bleriot  Flying  from  Etampes  to  Orleans 43 

2. — View  in  Paris  Aeronautical  Exhibition — October,  1009 65 

3. — Layout  of  Gores  for  Spherical  Balloon 76 

4. — Giffard's  Dirigible  Balloon 80 

5.— Tissandier's    Dirigible    Balloon 81 

6. — Renard's  and  Krebs'  Dirigible  Balloon 82 

7. — Texture  of  Modern  Balloon  Fabrics 65 

8. — Modern  Spherical   Balloon 90 

9. — Shuttles  for  Knotting  Balloon  Nettings,  and  Some  Typical  Knots.  .  104 

10.— Balloon  Valve   108 

11. — Car  of  Modern  Spherical  Balloon 90 

12. — Curious  Drag  Rope  of  Wellman  Dirigible 94 

13. — Internal  Balloon Ill 

14. — Balloon  House  for  Dirigible  "Russie" 94 

15. — Portable  Balloon  House  Used  by  the  French  Army 96 

16. — Balloon  Houses  Nearing  Completion 96 

17. — Rigid  Construction  of  Zeppelin  Dirigible 100 

18.— Dirigible  Balloon,  "Ville  de  Nancy" 104 

19.— Side  View  of  Nacelle  of  Wellman  Dirigible 108 

20.— Front  view  of  Nacelle  of  Wellman  Dirigible 108 

21.— Malicot   Semi-Rlgid  Dirigible   Balloon 104 

22.— Nacelle  of  the  French  Dirigible,  "Zodiac  III" 104 

23". — Count  de  Lambert  Piloting  Wright  Biplane 117 

24. — Degen's  Orthogonal  Flier 120 

25. — Trouve's  Flapping  Flier : 121 

26. — Engine  and  Wing  Mechanism  of  Hargrave  Model  No.  18 122 

27. — Collomb  Ornithopter    126 

28. — Toy  Helicopter   127 

29.— Toy  Helicopter   128 

30.— Toy  Helicopter 128 

31. — Bertin  Helicopter 126 

32. — Cornu  Helicopter 140 

33. — Bertin  Helicopter-Aeroplane 140 

34.— Box  Kite 133 

35. — Montgomery  Aeroplanes  of  1884-5,  with  Hinged  Ailerons  in  Wings.  140 

36.— Le  Bris'  Glider 155 

37. — Moy's  Aerial  Steamer   156 

38.— Flying  Fish 161 

39.— Flying  Frog 164 

40. — Comparison  of  Pterodactyl  and  Condor 166 

41. — Wing-case  Insect    166 

42. — Pressure  on  Vertical  and  Inclined  Surfaces 171 

43. — Plane  and  Arched  Surfaces  without  Angle  of  Incidence 172 

44  to  67. — Geometrical  and  other  Drawings  Explaining  the  Formation 

and  Action  of  Wing  Surfaces 176-199 

68. — Staggered  Biplane   205 

69. — Goupy  Biplane 158 

70. — Langley's  25-Pound  Double  Monoplane 208 

71. — Internal  Framing  of  Antoinette  Monoplane  Wing 158 

72. — Framing  of  Antoinette  Wing  Inverted 158 

73. — Framing  of  Bleriot  Monoplane  Wing 164 

74. — Inverted  Upper  Wing  Frame  of  Wright  Biplane 164 

75. — Assembling  Wright  Wing  Frames 170 

76. — Aileron  Control  of  Lateral  Balance  in  Antoinette  Monoplane 170 

77. — Aileron  Control  of  Bleriot  Monoplane  VIII 170 

78. — Lejeune  Biplane  with  Double  Aileron  Control 174 

79. — Front  View  of  PIschoff  and  Koechlin  Biplane 174 

80.— Side  View  of  Pischoff  and  Koechlin  Biplane 174 

17 


18  VEHICLES  OF  THE  AIR 

PlOUBE.  PAGE. 

81. — Aileron  Control  of  Farman  Biplane 174 

82.— Sliding  Wing  Ends 218 

83. — Swinging  Wing  Ends 219 

84. — Wright  Flexible  Elevator  or  Rudder 225 

85. — Rear  Controls  of  Antoinette  Monoplane 226 

86. — Double  Control  from  Single  Wheel 226 

87. — Shoulder-Fork  Control 228 

88. — Frame  of  New  Voisin  Biplane 230 

89. — Fuselage  of  Bolotoff  Monoplane 230 

90. — Feathering-Paddle  Flying  Machine 232 

91.— Partially-Housed  Paddle  Wheel 233 

92. — Wave  Surface 233 

93. — Helices  of  Propeller  Travel 239 

94. — Circles  of  Propeller  Travel 239 

95. — Diagram  of  Propeller  Pitch 240 

96. — Angle  of  Propeller  Blade  to  Angle  of  Travel 242 

97. — Advancing  and  Following  Surfaces 248 

98. — Three-Bladed  Propeller   231 

99. — Four-Bladed  Propeller 231 

100. — Chauviere  Walnut  Propeller 234 

101. — Propeller,  Engine,  and  Wing  Frame  of  Antoinette  Monoplane 234 

102. — Engine  and  Propeller  of  Santos-Dumont  Monoplane 234 

103. — Wooden  Propeller  of  Clement  Dirigible  Balloon 240 

104.— All-Metal  Propeller  Applied  to  Dirigible  Balloon 240 

105. — Straight,  Dihedral,  and  Curved  Propellers 252 

106. — Effect  of  Gyroscopic  Action  of  Single  Propeller  on  Steering 263 

107. — Twin  Wood  Propellers  on  Single  Shaft 264 

108. — Working  Drawings  of  a  Wooden  Propeller 266 

109. — Templets  for  Securing  a  Desired  Form  in  a  Wooden  Propeller 271 

110. — Four  Cylinder  Motor  of  Wright  Biplane 273 

111. — Pump-Fed  Antoinette  Engine 273 

112. — Three-Cylinder,  22-Horsepower  Anzani  Engine 276 

113. — Four-Cylinder — "Double-Twin" — Anzani    Motor 278 

114. — Renault  Eight-Cylinder  V-Shaped  Motor 278 

115. — Fiat  and  Panhard  Aeronautical  Motors 280 

116. — Darracq  and  Dutheil-Chalmers  Aeronautical  Motors 280 

117. — Diagram  of  Revolving-Cylinder  Motor 283 

118. — Gnome  Revolving-Cylinder  Motor 284 

119. — Ten-Cylinder  Motor  with  Concentric  Exhaust  and  Inlet  Valves 276 

120.— Magnetic  Plug 285 

121.— Make-and-Break  Ignition    285 

122. — Mechanical-Break  Jump-Spark  Ignition  System 286 

123.— Jump-Spark  Ignition   286 

124.— Hot-Tube  Ignition    287 

125. — Fuel-Injection  Aeronautical   Engine 290 

126.— Carbureter 292 

127.— Mietz  and  Weiss  Fuel  Pump 295 

128.— Silencer    296 

129.— Muffler 296 

130. — Steam  Engine  for  Aeronautical  Use 300 

131.— Flue  Boiler 302 

132.— Water-Tube  Boiler  for  Aeronautical  Use 300 

133.— Aeroplane  Power-Transmission  System 3 

134. — Aeroplane  Power-Transmission  System 3 

135. — Aeroplane  Power-Transmission  System 3 

136. — Aeroplane  Power-Transmission   System 313 

137.— Block  Chain 316 

138.— Roller  Chain 317 

139. — Chain  Transmission  of  Wright  Biplane 3 

140. — Chain  Transmission  in  Hydroplane,  Driven  by  Aerial  Propellers..  .   3 

141. — Belt  Transmission  in  Recent  Santos-Dumont  Monoplane 316 

142._Voisln  Biplane  Modified  Into  a  Triplane 327 

143. — Henry  Farman's  Biplane  in  Flight 327 

144._Adjustable   Ball   Bearing    329 

145.— Annular  Ball  Bearing 330 

146.— Full  Type  Annular  Ball  Bearing 332 

147.— Annular  Ball  Bearing 332 

148.— Annular  Ball  Bearing 332 


LIST  OF  ILLUSTRATIONS  19 

FIGURE.  PAGE. 

149. — Annular  Ball  Bearing  Subjected  t«  Thrust 333 

150.— Ball  Thrust  Bearing 334 

151. — Resultants  of  Load  on  Ball  Bearing. 335 

152. — Cylindrical  Roller  Bearing 340 

153.— Flexible   Roller   Bearing 341 

154.— Projected  Area  of  Plain  Bearing 345 

155. — Adjustment  of  Plain  Bearing 346 

156. — Cone  bearing . . 346 

157.— Bleriot  XI.  in  Flight 347 

158.— Bleriot  XII.  in  Flight 347 

159.— Ring  Oiler  on  Crankshaft 349 

160.— Force-Feed  Lubricator 351 

161. — Wright  Biplane  Starting  and  in  Flight 348 

162. — Koechlin  Monoplane  in  Flight 350 

163.— Wright  Machine  on  Starting  Rail 350 

164.— Bleriot  Alighting  Gear 350 

165. — Wright  Starting  System 358 

166.— Wright  Machine  and  Starting  Derrick 360 

167. — Starting  by  Rope  Attached  to  Stake  and  Wound  in  on  Drum 364 

168. — Rougier's  Voisin  Rising  from  Starting  Ground 360 

169. — Bleriot   Starting  Device 368 

170.— Typical  Alighting  Gear 368 

171. — Details  of  Bleriot  Monoplane 370 

172.— Alighting  Gear  of  Paulhan's  Voisin 370 

173. — Elevating   Montgomery   Aeroplane   with   a   Balloon,   in   California, 

in  1905 372 

174. — Alighting  Gear  of  Farman  Machine 374 

175.— Boat-Like  Body  of  Antoinette  Monoplane . . . 374 

176. — Alighting  Gear  of  Antoinette  Monoplane 374 

177. — Built-Up  Bamboo  Spar v 376 

178. — Sections  of  Wooden  Spars 380 

179. — Built-Up  Hollow  Wooden  Spar 381 

180. — Built-Up  Bamboo,  Hickory,  and  Rawhide  Wing  Bar 381 

181.— Methods  of  Fastening  Wire  Ends 386 

182.— Strut  Sockets  and  Turnbuckles 387 

183. — Wire  Tightener 387 

184. — Texture  of  Modern  Aeroplane  Fabrics 372 

185. — Scale  Drawings  of  Wright  Biplane 392 

186.— Side  View  of  Wright  Machine 394 

187.— Three-Quarters  View  of  Wright  Machine 394 

188.— Rear  View  of  Wright  Machine 398 

189.— Paul  Tlssandier  Seated  in  Wright  Biplane 400 

190. — Count  de  Lambert  In  Wright  Biplane 400 

191.— Wilbur  Wright  Instructing  a  Pupil 400 

192.— Details  of  Wright  Strut  Connections 402 

193. — Side  View  of  Wright  Runner  Construction 402 

194.— Wright  Runner  and  Rib  Details 402 

195.— Rudder  Frame  of  Wright  Machine 404 

196. — Elevator  Frame  of  Wright  Machine 404 

197.— Scale  Drawings  of  Bleriot  Monoplane  Number  XI * 406 

198.— Bleriot  Monoplane  Number  XII 408 

199. — Bleriot   Monoplane   Number   XI 408 

200.— Front  View  of  Bleriot  XI 408 

201.— Three-Quarters  View  of  Bleriot  XI 408 

202. — Scale  Drawings  of  Cody  Biplane 412 

203. — Latest  Model  of  Voisin  Biplane 414 

204. — Three-Quarters  Rear  View  of  Voisin  Biplane 414 

205. — Three-Quarters  Front  View  of  Voisin  Biplane 414 

206. — Scale  Drawings  of  Farman  Biplane 414 

207. — Side  View  of  Farman  Biplane 418 

208. — View  of  London-Manchester  Farman  Biplane 418 

209. — Maurice   Farman's    Biplane 420 

210. — Front  View  of  Maurice  Farman's  Biplane 420 

211.— Farman's   Modified  Voisin T. 420 

212. — Scale  Drawings  of  Antoinette  Monoplane 397 

213.— Three-Quarters  View  of  Antoinette  III 424 

214.— Rear  View  of  Antoinette  V 424 

215.— Front  View  of  Antoinette  VII 424 

216.— Rear  View  of  Antoinette  VII 426 

217. — Side  View  of  Santos-Dumont's  Belt-Driven  Monoplane.  ..  .7777. ..  426 


20  VEHICLES  OF  THE  AIR 

FIGURE.  PAGE. 

218. — Front  View  of  Santos-Dumont's  Belt-Driven  Monoplane 426 

219. — Side  View  of  Santos-Dumont's  Demoiselle 424 

220. — Front  View  of  Santos-Dumont's  Demoiselle 426 

221. — Scale  Drawings  of  Santos-Dumont's  Monoplane 428 

222.— Side  View  of  B.  E.  P.  Monoplane 430 

223. — Three-Quarters  View  of  R.  E.  P,  Monoplane 430 

224.— Captain  Ferber's  Dihedral   Biplane 430 

225. — Scale  Drawings  of  Montgomery  Glider 432 

226.— Side  View  of  Montgomery  Monoplane  Glider 434 

227. — Side  View  of  Small  Power  Propelled  Montgomery  Double  Monoplane  434 

228. — Scale  Drawings  of  Curtiss  Biplane 401 

229.— Side  View  of  Latest  Curtis  Biplane 436 

230.— Early  Lllienthal  Monoplane  Glider 405 

231.— Lilienthal  Monoplane  Glider 405 

232.— Lilienthal's    Biplane 405 

233.— Pilcher  Glider 407 

234.— Pilcher   Glider 408 

235.— Maxim  Multiplane 406 

236.— Maxim  Multiplane 406 

237.— Chanute  Biplane  Glider 398 

238. — Santos-Dumont's  Demoiselle  in  Flight 410 

239. — Paulhan's  Voisin  In  the  Douai-to-Arras  Flight 410 

240. — Suggested  Nernst  Lamp 413 

241.— Lens  Mirror 418 

242. — Locomotive  Headlight 419 

243. — Anemometer  Speed  and  Distance  Recorder 421 

244.— Universal  Level 426 

245.— Side  View  of  Bleriot  XI.  with  Wings  Tied  on  Frame 427 

246. — Front  View  of  Bleriot  XL,  Showing  Demountable  Wings 427 

247.— Assembling  Bleriot  XI .427 

248. — Wicker  Chair  and  Foot  Control  of  Ailerons  in  Farman  Biplane. . . .  440 

249. — Cockpit  of  Bleriot  Monoplane  Number  XI 440 

250. — Seating  Arrangement  and  Control  System  of  Antoinette  Monoplane  448 

251.— Sling  Seat  of  Captain  Ferber's  Biplane 448 

252. — Cockpit  and  General  Details  of  R.  E.  P.  Monoplane 450 

253. — Latham's  Antoinette  Monoplane  in  the  English  Channel 450 

254.— General  View  of  Paris  Aeronautical  Salon 452 

255. — Suggested  Use  of  Exhaust  Gases  to  Heat  Foot  Warmer 441 

256.— Parachute 442 

257.— Effect  of  Height  Upon  Choice  of  Landing 447 

258.— United  States  Weather  Signals 450 

259.— Wright  Patent  Drawings 453 

260. — Montgomery  Patent  Drawings 459 

261. — Chanute  Patent  Drawing 462 

262.— Mouillard  Patent  Drawing 463 

263.— Lilienthal  Patent  Drawing 464 

264. — Diagrammatic  Comparisons  of  Modern  Aeroplanes 473 

265. — Flights  over  English  Channel 474 

266. — Farman  Flights,  Chalons  to  Rheims,  and  Chalons  to  Suippes 474 

267. — Count  de  Lambert's  Flight  over  Paris 474 

268. — Map  Showing  Principal  Zeppelin  Flights 475 

269. — Flight  of  Paulhan  and  Grahame-White,  London  to  Manchester 476 

270.— Flight  of  Curtiss  from  Albany  to  New  York  City 476 


"F or  centuries  we  stood  upon  the  edge 
Of  space  and  yearned,  while  sparrows  from  the  hedge 
Took  flight  and  taunted  us.     'That  I  had  wings!' 
'Mid  stormy  music,  thus  the  Psalmist  sings, 
'Then  would  I  fly  away  and  be  at  rest.' 
And  lo,  the  wings  are  ours,  a  gift,  the  best 
The  genius  of  our  race  has  forged. 


"     *     *     *     What  narrow  space 

Holds  man  to-day  apart  from  brother  man, 

A  range  of  rock,  a  river  or  a  span 

Of  channel;  and  our  wings  shall  overleap 

These  dwarfish  landmarks.     *     *     *  " 

CHARLTON  LAWRENCE  EDHOLM. 


INTRODUCTION         .  >   .   ,    _, 

To  the  preparation  of  this  work,  the  author  has  been 
influenced  largely  by  the  lack  of  any  concrete  and 
popular  treatise  on  aerial  navigation. 

With  the  obJect  of  remedying  this 
condition  in  at  least  some  degree  it 
has  been  sought  to  produce  an  adequate,  up-to-date, 
and  at  the  same  time,  a  comprehensive  presentation  of 
what  is  fast  becoming  one  of  the  most  important  and 
alluring  fields  of  modern  engineering.  In  the  accom- 
plishment of  this  purpose  it  has  seemed  desirable  to 
plan  a  volume  that  should  appeal  to  general  curiosity 
as  well  as  to  particular  interest.  This  is  because  the 
subject  is  so  new  that  few  can  lay  any  claim  to  its  mas- 
tery, though  thousands  are  commencing  its  study. 

These  conceptions  of  the  need,  and  of  the  sort  of 
interest  to  be  met  by  a  book  of  this  character,  have 
dictated  the  inclusion  not  only  of  timely  and  authori- 
tative data  concerning  contemporary  successes,  but 
also  of  some  material  that  is  chiefly  historical — often 
the  history  of  now  discredited  mechanisms — as  a  help 
in  easily  and  clearly  conveying  to  the  casual  reader  a 
logical  idea  of  just  wKat  progress  has  been  made  and 
is  making  in  the  modern  science  of  aeronautics.  It 

21 


22  VEHICLES  OF  THE  AIR 

even  has  appeared  reasonable  to  venture  occasional 
suggestions  of  the  future — forecasts  intended  simply 
to  stimulate  still  doubtful  imaginations  rather  than  to 
invalidate  themselves  by  too-complicated  or  far-fetched 
premises.  Yet  in  such  prophecies  it  will  be  readily 
appreciated  by  the  technically  versed  that  the  prophet 
is  sufficiently  safe  if  he  don  his  robe  without  too  reck- 
less a  disregard  of  his  limitations,  and  confine  himself 
to  Impressing  upon  the  general  attention  only  such 
.fasg-ts  .as;  are  already  evident  and  obvious  to  the  few 
spe'cialists  who  are  closely  in  touch  with  their  subject. 

Necessarily  some  portion  of  the  matter  herein  pre- 
sented is  in  a  way  the  product  of  compilation.  It  being 
the  province  of  the  writer  at  a  task  of  this  sort  to 
record  rather  than  to  create,  it  is  not  to  be  expected 
that  much  more  can  be  accomplished  than  a  discrimi- 
nating and  consistent  addition  of  new  material  to  old, 
with  the  two  arranged  and  related  in  an  orderly  and 
informing  manner.  No  more  than  this  has  been 
attempted ;  if  no  less  has  been  accomplished  the  author 
will  feel  well  satisfied. 

The  publishers  join  with  the  author  in  the  hope 
that  this  book  may  help  to  stimulate  the  English- 
speaking  races  into  some  parallel  with  foreign  enthu- 
siasm in  aeronautics.  For  it  seems  as  true  as  it  is 
regrettable  that  the  nations  that  developed  the  Wright 
brothers,  Montgomery,  Chanute,  Langley,  Herring, 
Pilcher,  Stringfellow,  Wenham,  Hargrave,  Henson, 
Maxim,  McCurdy,  Curtiss,  and  others,  and  which  once 
were  found  always  in  the  van  of  the  world's  progress 
in  science  and  invention,  are  replacing  their  one-time 
zeal  for  promising  innovations  and  scorn  of  hampering 
precedents  with  an  imitative  and  trailing  commer- 
cialism, of  which  there  already  has  been  at  least  one 


INTRODUCTION  23 

other  sufficient  example.  Certainly  it  is  an  inescapable 
fact  that  the  less  tradition-trammeled  engineers  of 
continental  Europe  are  the  first  to  perceive  the  begin- 
nings of  the  practical  and  commercial  era  in  aero- 
nautics, just  as  they  were  the  first  to  perceive  it  in 
the  case  of  the  automobile.  And  equally  is  it  a  fact 
that  the  United  States  and  the  British  governments, 
and  American  and  English  capitalists,  continue  con- 
spicuously tardy  in  their  recognition  of  the  newest  and 
least-limited  advance  in  the  history  of  transportation. 


Nothing    but    the    utmost    blindness    to    existing 
achievements  can  continue  to  belittle  what  it  cannot 

comprehend.    Aerial  navigation  today 
SKEPTICISM     .  •  i     ,1  j,        ., 

is  IGNOBANCB    1S  no  more  a  Joke  tnan  was  ^ne  railway 

eighty  years  ago,  or  the  steamship 
seventy  years  ago,  or  the  automobile  ten  years  ago. 
On  the  contrary,  it  is  already  the  basis  of  a  vast  and 
progressing  industry,  founding  itself  surely  on  the 
most  advanced  discoveries  of  exact  science  and  the 
finest  deductions  of  trained  minds,  and  possessed  of 
a  future  that  in  its  sociological  as  well  as  in  its  engi- 
neering aspects  sooner  or  later  must  stir  the  imagina- 
tions of  the  dullest  skeptics.  Inevitably  it  is  a  matter 
of  perhaps  no  more  than  a  few  months — certainly  of 
no  more  than  a  few  years — after  this  is  written  when 
in  every  country  of  the  world  aerial  vehicles  will  enter 
upon  an  epoch  of  wide  development  and  application, 
the  far-reaching  reactions  of  which  are  certain  to  carry 
significances  of  the  profoundest  import  to  every  phase 
of  civilization  and  every  activity  of  the  race. 

Man's  movements  about  the  planet  he  inhabits  are 


24  VEHICLES  OF  THE  AIR 

restricted  to  a  maximum  of  the  three  traversable  media 
with  which  he  can  come  in  physical  contact.  He  can 
THREE  travel  by  land,  by  water — and  by 
TRAVEESABLE  air.  Of  the  difficulties  of  these,  he  first 
MEDIA  overcame  the  simplest,  as  was  to  have 
been  expected;  he  next  fell  to  devising  one  kind  and 
another  of  water  craft,  and  progressed  to  navigation 
of  the  seas;  and  now,  after  centuries  of  ineffective 
struggle,  he  is  beginning  to  apply  the  hard-won  les- 
sons of  his  slowly-accumulated  knowledge  to  the  con- 
quest of  the  air.  Of  the  three  media,  the  air  alone 
exists  over  the  earth's  entire  surface,  thus  demanding 
for  its  utilization  neither  specially-constructed  high- 
ways nor  restriction  of  journeys  such  as  limit  or  make 
costly  all  efficient  transportation  on  land  and  water. 
And,  more  than  this,  as  there  are  unknowable  forces 
greater  than  the  mere  opinions  and  activities  of  men 
so  is  it  only  consistent  with  experience  of  human 
progress  and  observation  of  the  eternal  logic  of  things 
to  recognize  that  sooner  or  later  mankind  must  con- 
quer this  last  highway  of  the  world,  thus  finally  assert- 
ing the  dominion  over  all  things  terrestrial  that  is 
declared  his  right  by  the  scriptures. 

Concerning  the  types  of  machines  that  will  survive, 
as  most  successfully  applicable  to  practical  and  com- 
mercial  navigation  of  the  air,  present 
knowledge  is  distinctly  informing.  It 
seems  rather  clearly  indicated,  for 
example,  that  the  "lighter-than-air"  type,  the  balloon, 
can  have  little  future  beyond  such  as  is  too  often 
founded  upon  the  activities  of  ignorant  inventors  or 
unscrupulous  promoters,  or  upon  the  thrills  it 
undoubtedly  affords  as  a  Gargantuan  spectacle.  As  is 
hereinafter  suggested  the  balloon  is  an  evasion  rather 


INTRODUCTION  25 

than  a  solution  of  the  real  problems  of  aerial  naviga- 
tion. It  floats  in  the  air  rather  than  navigates  it, 
wherefore  it  is  no  more  a  flying  machine  than  a  cork  in 
the  sea  is  an  ocean  liner.* 

The  helicopter  is  the  type  of  "heavier-than-air" 
machine  designed  to  ascend  by  the  action  of  one  or 
more  lifting  propellers,  rotating  on  vertical  axes.  The 
type  must  for  the  time  be  dismissed  as  without  present 
status  to  condemn  or  approve  it.  It  is  enough  to  say 
that  more  than  one  engineer  of  unquestioned  eminence 
has  faith  in  it,  while  there  are  others  of  equal  standing 
who  as  positively  disapprove. 

The  term  ornithopter  is  given  to  any  type  of 
heavier-than-air  machine  in  which  there  is  attempted 
imitation  of  nature's  wing  motions.  The  matter  of 
its  merits  comes  down  chiefly  to  the  simple  question  of 
whether  or  not  a  reciprocating-wing  system  can  be 
made  superior  in  reliability  and  efficiency  to  the 
rotating-wing  system  that  constitutes  a  propeller. 
Probably  no  engineer  of  practical  abilities  will  con- 
tend that  it  can.  It  is  a  common  argument  that  birds, 
which  may  be  considered  the  flying  machines  par 
excellence,  fly  on  this  plan.  Admittedly  true,  but  it  is 
equally  true  that  most  animals  walk  on  legs  and 
most  fishes  swim  with  tails  and  fins,  despite  which 
man  finds  that  with  wheels  and  screw  propellers  he 
can  secure  results  vastly  superior  to  any  that  are  to 
be  found  in  attempts  to  copy  nature's  mechanisms 
more  closely.  It  is  a  point  deserving  of  regard  in 

*It  being  a  fact,  however,  that  the  dirigible  balloon  exists,  and  that 
its  problems  are  enlisting  the  activities  of  able  engineers  and  powerful 
governments,  for  these  reasons  it  will  herein  in  all  fairness  be  accorded 
such  attention  as  seems  demanded  by  its  present  prominence  rather  than 
by  its  future  prospects. 


26  VEHICLES  OF  THE  AIR 

this  connection  that  the  real  reason  the  continuous 
rotating  mechanism  is  unknown  in  the  animal  economy 
may  be  the  most  excellent  one  that  it  is  not  available. 
A  wheel  or  any  similar  continuous-rotating  element  in 
a  machine  involves  a  complete  separation  of  parts, 
mere  contact  or  juxtaposition  being  substituted  for  the 
complete  structural  continuity  that  is  rendered  impera- 
tive in  the  natural  machine  by  nature's  self-contained 
processes  of  manufacture,  growth,  and  repair — proc- 
esses with  which  man's  mechanisms  are  not  handi- 
capped, however  imperfect  they  may  be  in  other 
respects. 

The  aeroplane  is  far  and  away  the  most  promising 
of  the  several  types  of  machines  in  so  far  as  any 

AEROPLANE     present  vision  can  discern.    This  type 
MOST  of  air  craft  is  sustained  by  the  reac- 

SUCCESSFUL  tions  of  the  air  rotations  and  streams 
under  and  adjacent  to  its  inclined  curved  surfaces, 
and  in  nature  finds  its  analogy  in  the  soaring  bird, 
and  particularly  in  certain  insects.  Ordinarily,  to  fly, 
an  aeroplane  must  keep  moving,  wherefore  it  must 
attain  lateral  speed  before  it  can  rise,  and  must  retard 
to  a  stop  in  alighting.  Without  exception  all  the  suc- 
cesses recently  achieved  in  the  United  States  and 
abroad  have  been  with  curved- wing*  aeroplanes. 

The  questions  of  speed  and  flying  radius  are  still 
some  way  from  any  sort  of  settlement.  Certainly  the 
speeds  ultimately  attained  will  be  very  high,  but,  what 
is  more  to  the  point,  they  will  be  easily  maintained. 
In  this  regard  aerial  navigation  is  comparable  with 

*The  modern  substitution  of  curved  surfaces  for  the  flat  ones  of 
earlier  experiments  has  made  the  term  ' '  aeroplane ' '  a  misnomer,  but  it 
seems  nevertheless  to  have  fixed  itself  ineradicably  upon  the  language, 
and  so  may  as  well  be  accepted. 


INTRODUCTION  27 

travel  on  water  rather  than  with  travel  on  land, 
maximum  speeds  being  also  average  speeds  in  the  case 
of  the  steamship,  though  this  is  not 
the  case  with  land  locomotion.  In 
addition  to  its  other  advantages, 
high  speed  of  aerial  travel  may  prove  the  soundest 
engineering  because  it  admits  of  sustaining  the 
heaviest  loads  upon  the  smallest  surfaces.  Another 
and  imperative  reason  for  speed  will  be  to  overcome 
adverse  winds.  To  progress  against  wind,  speed 
higher  than  the  highest  wind  in  which  flying  is  to 
be  attempted  may  be  required.  The  limit  of  wind 
velocity  with  which  it  may  prove  possible  to  battle 
will  be  determined  mainly  by  conditions  of  starting 
and  landing. 

As  for  the  possible  radii  or  action — the  maximum 
distances  of  travel  without  return  to  a  base  or 
descent  to  the  earth  for  additional  supplies  of  fuels, 
lubricants,  etc. — it  is  evident  at  the  outset  that  the 
greater  the  radius  the  greater  the  utility.  Indeed,  the 
ability  to  combat  long-continued  adverse  winds,  appli- 
cation to  polar  and  other  exploration,  transoceanic 
travel,  and  sustained  rapid  transit  overland  may  hinge 
directly  upon  capacity  to  accomplish  great  distances  on 
minimums  of  supplies  and  fuel. 

The  sizes  of  the  machines  that  will  be  built  is 
another  matter  for  the  future  to  determine.  It  being 
a  law  of  geometry  that  the  areas  of  structures  increase 
with  the  squares  of  their  linear  dimensions,  while 
bulks  and  weights  increase  with  the  cubes,  it  is  evident 
that  at  some  point  the  gain  of  the  weights  over  the 
areas  will  impose  a  limit  that  cannot  be  passed. 
Against  this,  however,  is  the  likelihood  that  there  may 
not  be  much  use  for  large  craft.  Traffic  experts  agree 


28  VEHICLES  OF  THE  AIR 

that  the  secret  of  all  rapid  transit  is  the  maintenance 

of  speed,  it  being  the  slo wings  down  and  the  stops  that 

chiefly  account  for  the  slow  average 

AEROPLANES  sPee(^s  on  ^an(^  despite  the  wonder- 
ful spurts  that  have  been  made  by 
land  vehicles  for  short  distances.  Most  evidently,  the 
existence  of  the  expensive  large-unit  vehicle  on  land 
is  mainly  due  to  the  necessity  for  highly-specialized, 
prepared  highways,  while  on  water  it  has  been  found 
an  essential  means  to  high  speeds  and  maximum 
safety.  In  the  air  conditions  will  be  different.  Here 
the  inexpensive  and  ideal  small-unit  vehicle,  suggested 
in  some  degree  by  the  automobile,  and  likewise  eman- 
cipating its  user  from  other  persons'  routes,  stops, 
and  time  schedules,  will  find  an  unlimited  field  for 
development.  Moreover,  such  development  will  pro- 
gress under  the  stimulus  of  lower  first  and  maintenance 
costs  than  apply  to  any  other  system  of  travel. 

Flying  machines  will  be  inexpensive  to  build 
because  their  construction  calls  for  little  use  of 

FIRST  AND      complex   forms   in   resistant   metals. 

OPERATING  Wood,  wire,  and  fabric  of  common 
qualities  and  at  low  cost  are  almost 
the  extent  of  what  is  necessary,  barring  tlie  question 
of  motors,  which  will  be  cheaply  manufactured  in 
quantities,  to  standardized  designs.  And  even  more 
vital  than  mere  low  cost  of  manufacture  will  be  the 
fact  that  manufacture  will  not  require  the  facilities  of 
costly  factories,  but  can  be  undertaken  by  any  one 
possessed  of  the  requisite  data  and  an  ordinary  sort  of 
carpentering  ability. 

That  flying  machines  will  be  inexpensive  to  operate 
must  reasonably  follow  from  the  small  power  needed 
for  their  propulsion  and  from  the  fact  that  they  have 


INTRODUCTION  29 

no  working  parts  in  constant  destructive  contact  with 
a  roadway.  Indeed,  the  transition  from  the  expedient 
of  confining  air  in  automobile  tires  to  the  utilization 
of  the  unconfined  air  of  the  atmosphere  as  a  vehicle 
support  is  rather  definitely  an  advance  from  a  lower 
to  a  higher  order  of  engineering. 

Nor  are  these  questions  of  cost  in  any  sense  the 
least  important  factors  in  the  future  of  aerial  naviga- 
tion. Modern  engineering  abounds  in 
T*ASPECT  examples  of  things  that  are  possible 
but  not  profitable.  Indeed,  it  is  just 
this  point,  that  limited  utilities  do  not  warrant  unlim- 
ited expenditures,  that  so  utterly  condemns  the  dirig- 
ible balloon.  With  flying  machines,  sufficing  for  the 
safe,  inexpensive,  and  rapid  conveyance  of  one  or  two 
persons,  cheaper  to  build  than  a  modern  motorcycle, 
there  enter  prospects  that  must  ultimately  loom  larger 
on  the  horizon  of  transportation  and  the  whole  struc- 
ture of  modern  society  than  even  so  great  a  prospect 
as  the  actual  accomplishment  of  aerial  navigation 
itself.  Laws,  customs,  and  conventions  must  fall  in 
the  tremendous  readjustments  that  will  ensue.  Many 
forms  of  social  trespass  will  have  to  be  fought  by 
removal  of  incentives  rather  than  by  attempts  at  pun- 
ishment, and  there  will  be  discovered  innumerable 
outlets  for  various  movements  for  race  improvement, 
which  the  iron  inflexibility  of  present-day  environment 
keeps  suppressed  and  silent. 

Questions  of  safety  are  ever  uppermost  in  most 
persons '    contemplations    of   aerial    travel.    To    the 
average  individual  let  there  be  said 
flying  machine  and  at  once  his  brain 
must  visualize  some  horrifying  con- 
ception of  an  unstable  craft  of  vague  outlines  and 


30  VEHICLES  OF  THE  AIR 

terrible  hazards,  precariously  poised  in  the  cloudland 
at  an  illimitable  height  above  terra  firma.  How  dis- 
tinctly such  ideas  are  at  variance  with  the  facts  has 
been  shown  by  the  Wright  brothers,  Farman,  Bleriot, 
and  others,  in  flying  for  mile  after  mile  only  four  or 
five  feet  from  the  ground.* 

People  are  prone  to  appraise  casualty  by  its  horror 
rather  than  by  its  statistics,  and  the  thought  of  one 
individual  tumbling  from  the  skies  grips  harder  on 
the  popular  imagination  than  the  slaughter  of  a  few 
scores  in  a  railway  accident  or  the  drowning  of  a  few 
hundreds  in  a  shipwreck.  As  a  matter  of  fact,  there 
are  many  more  factors  of  safety  in  present  and  pros- 
pective aerial  travel  than  at  first  appear,  even  to  the 
well-informed.  Besides  the  proved  practicability  of 
close-to-the-ground  flight,  there  is  in  the  case  of  the 
aeroplane  the  complete  stability  of  the  type  as  a 
glider.f  This  means  that  the  immediate  safety  at 
any  moment  is  not  contingent  upon  the  operation  of  a 
more-or-less  complicated  motor,  the  continued  func- 
tioning of  which  is  dependent  upon  the  unfailing 
operation  of  an  interconnected  aggregation  of  parts 
rapidly  revolving  or  reciprocating  under  heavy 
stresses.  On  the  contrary,  a  motor  is  necessary,  if 


*  In  teaching  Captain  Lucas  Gerardville  of  the  French  army  to 
operate  the  Wright  flyer,  Wilbur  Wright  required  the  control  of  the 
levers  to  be  returned  to  him  whenever  the  machine  was  steered  lower 
than  two  meters  (6%  feet)  or  higher  than  four  meters  (13  feet)  from 
the  ground,  thus  indicating  that  he  considered  inability  to  keep  within 
this  zone,  even  for  a  beginner,  as  definitely  incompetent  driving  as 
would  be  steering  out  of  the  road  with  an  automobile.  Such  close-to- 
the-ground  flight  is  particularly  well  shown  in  the  photographs  repro- 
duced in  Figure  161. 

f  The  Wright  machine  was  first  developed  as  a  glider  without  a 
motor,  and  in  its  later  motor-propelled  models  has  been  on  more  than 


INTRODUCTION  31 

at  all,  only  to  maintain  continued  upward  or  hori- 
zontal travel,  the  ability  to  soar  reliably  at  a  flat  angle 
down  a  slant  of  air  being  contingent  only  upon  the 
continued  structural  integrity  of  non-moving  elements, 
or  at  worst,  of  elements  readily  made  very  strong  or 
even  provided  in  duplicate,  and  demanding  only  mod- 
erate and  occasional  control  adjustment  against  very 
light  stresses.  As  a  consequence,  the  only  risk  likely 
to  continue  ever-present  is  that  of  such  derangement 
or  the  encountering  of  such  adverse  weather  condi- 
tions as  may  compel  landing  upon  unfavorable  areas 
without  immediate  but  with  the  prospect  of  ultimate 
disaster.  Thus,  to  be  compelled  by  engine  failure  or 
adverse  weather  to  descend  in  a  desert  or  forest,  or  on 
rough  mountains,  would  result  in  a  situation  fairly 
comparable  to  that  of  a  wrecked  vessel,  or  of  a  de- 
railed train,  or  of  a  ditched  automobile,  rather  than 
in  one  ascribable  to  any  undue  and  inherent  hazard 
pertaining  to  the  new  conveyance  regardless  of 
the  conditions  of  its  use.  These  different  con- 
siderations will,  however,  doubtless  produce  defi- 
nite effects  on  the  progress  that  will  be  made, 
and,  as  progress  continues  and  engineering  resource 

one  occasion  driven  to  considerable  altitudes,  the  engine  stopped  pur- 
posely or  inadvertently,  and  a  safe  soaring  descent  to  the  ground  ac- 
complished. The  Montgomery  machine,  built  primarily  as  a  glider,  can 
be  dropped  upside  down  in  the  air,  even  with  loads,  and  such  is  its 
automatic  stability  that  it  invariably  rights  itself  and  comes  to  the 
ground  as  gently  as  a  parachute.  The  Antoinette,  Bleriot,  Voisin, 
Curtiss,  R.  E.  P.  and  many  other  successful  flyers  likewise  have  proved 
safe  gliders  with  engines  stopped.  Particularly  significant  in  this  con- 
nection were  Latham's  two  descents,  enforced  by  engine  failure,  into 
the  waters  of  the  English  Channel — once  without  even  wetting  his  feet! 
Other  experiences  showing  that  engine  failure  does  not  necessarily  mean 
serious  disaster  have  become  very  numerous  within  the  past  few  months, 
(May,  1910)  in  the  use  of  practically  every  operative  aeroplane  that  has 
been  built. 


32  VEHICLES   OF  THE  AIR 

makes  of  the  trackless  air  an  unrestricted  highway 
of  ever-increasing  stability,  those  of  the  sky  pilots 
whose  temerity  is  greatest  may  be  expected  to  become 
more  and  more  venturesome  and  capable,  so  that  the 
development  of  the  flying  machine,  from  commencing 
with  cautious  flights  in  favorable  weather,  at  moderate 
speeds  and  low  altitudes,  and  over  surfaces  upon 
which  landing  is  comparatively  safe,  must  in  time  pro- 
gress to  exceedingly  rapid  travel  at  somewhat  greater 
heights,  and  with  less  regard  to  the  state  of  the 
weather  or  to  the  character  of  the  surface  beneath. 
Aerial  navigation  offers  little  prospect  of  ever 
becoming  safe  to  the  extent  of  relieving  those  who 
take  it  from  the  common  chances  of 

A^mAVEL      life     and     death>     but     it;     does     most 

emphatically  promise  that  its  hazards 
per  passenger  carried  a  given  distance  will  not  exceed 
the  corresponding  hazards  of  terrestrial  and  aquatic 
transportation.  The  railroads  of  the  United  States 
alone  exact  an  annual  toll  of  12,000  persons  killed  and 
72,000  injured,  yet  many  very  timid  individuals  think 
nothing  of  riding  for  hours  at  a  time,  at  speeds  of 
forty,  sixty,  and  eighty  miles  an  hour,  along  the  tops 
of  precipitous  embankments  and  over  unguarded 
bridges  and  trestles,  with  their  safety  never  for  a 
moment  independent  of  the  somewhat  precarious  hold 
of  thin  wheel  flanges  on  the  smooth  edges  of  narrow 
rails.  Thus  does  familiarity  breed  contempt.  Never- 
theless, compelled  to  a  choice  between  being  plunged 
to  the  ground  through  a  distance  of,  say,  fifteen  feet 
in  a  light,  elastic,  and  protecting  structure  of  wood, 
wire,  and  fabric,  against  the  proposition  of  rolling  a 
similar  distance  down  an  embankment,  surrounded  by 


INTRODUCTION  33 

the  crushing  mass  of  a  railway  coach,  what  sane  indi- 
vidual would  prefer  the  hazards  of  the  latter! 

As  progress  continues  and  safety  becomes  more 
and  more  assured  under  conservative  and  reasonable 
conditions,  the  timid  will  in  increasing 
FEAR  A  HABIT  num|jerg  venture  first  trips  as  pas- 
sengers and  be  reassured  by  their 
experiences,  until  the  time  will  arrive  when  to  fear  to 
travel  by  air  will  be  to  class  one  with  the  people  who 
today  are  afraid  to  dare  the  risks  of  rail  and  water 
travel.  A  gradual  overcoming  of  the  inertia  of  the 
mind  appears  to  be  an  essential  process  in  reconciling 
the  generality  of  people  to  innovations.  Even  in  the 
cases  of  many  institutions  of  the  longest  standing 
there  are  persistent  inconsistencies  in  many  people's 
attitudes.  For  example,  the  automobile,  which  com- 
pared " passenger-mile "  against  "passenger-mile"  is 
found  responsible  for  far  fewer  fatalities  than  regu- 
larly attend  the  use  of  horses,  still  is  regarded  as  a 
sort  of  death-dealing  juggernaut  by  many  normally 
sensible  persons.  Likewise,  it  is  commonplace  to  find 
people  thoroughly  hardened  to  travel  by  the  most  dan- 
gerous type  of  rail  vehicle,  the  street  car,  who  cannot 
restrain  a  feeling  of  terror  at  the  thought  of  travel 
by  steamship,  which  is  statistically  provable  to  be  any 
number  of  times  safer.  At  the  time  this  is  written  the 
power-driven  heavier-than-air  flyer  has  been  respon- 
sible for  the  death  of  only  eight  individuals  in  the 
whole  world,  despite  an  aggregate  of  experimental 
flights  totalling  fully  150,000  miles. 

Undoubtedly  the  first  commercial  applications  of 
aerial  vehicles  will  be  to  classes  of  service  involving 
minima  of  human  risk  with  maxima  of  utility — serv- 
ices such  as  the  conveyance  at  high  speed  of  special 


34  VEHICLES  OF  THE  AIR 

classes  of  mail  and  express  matter  by  aeroplanes,  each 

requiring  for  its  management  only  a  single  operator, 

or   the   rapid   distribution   of   news- 

COMMERCIAL  ,    •  i  .-n  ,•  -i 

APPLICATIONS  PaPer  matnces  and  illustrations  under 
similar  conditions.  Next  may  come 
the  daring  spirits  who  will  take  desperate  chances  in 
the  exploration  and  prospecting  of  remote  and  unset- 
tled regions — not  to  consider  the  red-blooded  few  who 
from  the  beginning  find  in  navigation  of  the  air  a 
new  means  of  reckless  sport  and  dangerous  recreation, 
chiefly  interesting  in  the  improvements  that  result 
from  their  successes  and  the  lessons  that  are  gleaned 
from  their  mishaps. 

To  any  one  who  has  kept  abreast  of  recent  progress 
it  is  genuinely  amazing  that  there  are  still  so  many 
who  question  this  matter  of  commercial  applica- 
tions. Many  who  even  concede  that  the  flying  machine 
may  find  important  application  in  warfare  and  meet 
with  considerable  success  in  sport,  still  are  disposed 
to  deny  that  it  ever  can  find  extensive  use  as  a  common- 
place, every-day  means  of  transportation.  Such  per- 
sons mistake  the  bounds  of  their  own  knowledge  for 
defects  in  the  thing  examined,  and  see  in  every  failure 
of  an  experimental  mechanism,  no  matter  to  what 
cause  due,  a  conclusive  condemnation  of  a  whole  propo- 
sition, and  when  they  find  themselves  astute  enough 
to  glimpse  a  limitation,  no  matter  how  trifling,  its  sub- 
traction from  the  original  quantity  clearly  leaves  a 
remainder  of  zero.  Yet  an  inability  to  fly  at  all 
through  not  knowing  how  is  a  distinctly  different 
thing  from  a  mere  cessation  of  flight  from  break- 
down. The  first  leaves  mankind  as  positively  unable 
to  travel  in  the  air  as  to  travel  to  Mars.  The  second 
is  with  perfect  reasonableness  comparable  with  such 


INTRODUCTION  35 

negative  disabilities  as  broken  flanges,  punctured  tires, 
leaking  hulls,  and  the  like,  which  similarly  may  termi- 
nate particular  trips  by  particular  means  in  delay  and 
even  in  death. 

As  for  limitations,  it  certainly  is  to  be  admitted, 

for    example,    that    the    aeroplane    appears    totally 

unsuited   for   urban   travel.     In  its 

IMITATIONS     present  most  SUCCeSSful  forms  it  re- 

EXPECTED  .  •    -i    -I       •  111 

quires  special  devices  or,  at  least,  con- 
siderable clear  and  unobstructed  areas  for  starting 
and  alighting.  But  for  interurban  travel,  on  the  other 
hand,  these  limitations  fail  to  constitute  objections  of 
material  magnitude.  There  is  no  more  reason  for 
expecting  the  aeroplane  to  find  its  utility  by  developing 
a  facility  in  maneuvering  through  mazes  of  wires  and 
alighting  amid  street  traffic  than  there  would  be  for 
condemning  Atlantic  liners  because  they  have  to  dock 
at  Hoboken  instead  of  sailing  up  Broadway.  Undoubt- 
edly the  time  will  come  when  it  will  be  considered 
quite  as  reasonable  that  the  beginnings  and  endings  of 
aerial  voyages  should  involve  the  presence  of  special 
launching  and  landing  facilities,  as  it  is  that  railway 
trains  should  travel  from  station  to  station.  No  type 
of  transportation  is  unlimitedly  flexible.  Kail  vehicles 
are  confined  to  rails,  automobiles  must  keep  to  roads 
or  good  surfaces,  water  craft  cannot  leave  the  water, 
bicycles  require  at  least  a  fair  path,  and  not  even 
beasts  of  burden  and  men  walking  can  disregard  all 
topographical  difficulties.  Against  these,  surely  the 
ability  of  the  air  vehicle  to  progress  in  an  air  line  at 
its  high  and  maintained  speed  from  selected  start  to 
selected  destination,  always  regardless  of  what  may 
be  beneath,  and  ever  ready  should  necessity  compel  to 
settle  under  control  and  without  immediate  danger 


36  VEHICLES  OF  THE  AIR 

upon  any  fair  area  of  unencumbered  land  or  water 
space,  may  be  regarded  as  a  form  of  flexibility  suffi- 
ciently valuable  to  offset  the  lack  of  other  sorts. 
Moreover,  there  is  some  reason  for  expecting  that 
small  aeroplanes  and  helicopters  may  arrive  ultimately 
at  such  reliability  and  perfection  of  control  that  it 
will  be  feasible  to  direct  them  from  or  upon  almost  any 
place  that  affords  space  to  accommodate  them. 

Particularly  interesting  is  the  relation  of  aerial 

navigation  to  war — it  appearing  more  than  probable 

that  this  latest  of  man's  inventions 

•RELATION  w^  serve  £rst  jn  adding  to  the  ter- 
rors of  and  then  in  the  laying  of  this 
grim  specter  of  the  centuries.  For  aside  from  all 
mere  tactical  questions  of  airships  versus  battleships 
it  is  most  of  all  to  be  considered,  as  a  very  few  mili- 
tary authorities  have  pointed  out,  that  in  the  develop- 
ment of  the  flying  machine  there  is  placed  for  the  first 
time  in  history,  in  the  hands  of  weak  and  strong  com- 
batants alike,  a  weapon  capable  of  as  effective  and 
unpreventable  direction  against  the  kings,  congresses, 
presidents,  and  diplomats  who  declare  war  as  it  is  of 
direction  against  the  fighting  men  on  the  faraway 
battlefronts.  Already  more  than  one  great  military 
and  naval  captain  has  suffered  disquieting  visions  of 
what  will  happen  when,  maneuvering  unopposed  and 
unseen  in  the  obscurity  of  the  night,  not  merely  one 
or  a  few,  but  veritable  swarms  of  light  aeroplanes,  in 
twenty-thousand  lots  costing  no  more  than  single 
dreadnoughts,  commence  trailing  assortments  of  high 
explosives  at  the  ends  of  thousand-foot  lengths  of 
piano  wire,  over  cities  and  palaces  and  through  fleets 
and  armies. 

Many  authorities  are  inclined  to  disparage  the 


INTRODUCTION  37 

fighting  utility  of  the  aeroplane,  basing  their  views  on 
the  fact  that  it  has  been  demonstrated  exceedingly 
difficult  to  drop  bombs  with  any  considerable  accuracy 
from  great  heights.  But  from  a  slow-moving  aero- 
plane flying  very  low  it  should  be  an  easy  matter  to 
cast  generous  parcels  of  picric  acid  or  fulminate  of 
mercury  into  the  twenty-foot  diameters  of  a  battle- 
ship 's  funnels.  The  answer  that  such  an  attempt 
might  be  foiled  by  the  use  of  searchlights  and  quick- 
firing  guns  is  one  that  contemplates  attack  by  only 
one  or  two  of  the  air  craft,  rather  than  to  the  con- 
certed descent  of  a  whole  host  of  such  emissaries  of 
destruction,  each  manned  by  a  competent  and  deter- 
mined crew,  realizing  that  if  only  one  of  the  wasp-like 
swarm  achieves  its  purpose  the  picking  off  of  a  few 
by  lucky  shots  or  extraordinary  gunnery  will  be  fear- 
fully avenged. 

Fancy  for  a  moment  the  disillusionment  to  come 

when  in  some  great  conflict  of  the  future  a  splendid 

up-to-date  battleship  fleet  of  the  traditional  order,  with 

traditional  sailors,  traditional  admiral,  and  traditional 

tactics,  finds  itself  beset  in  midseas  by  a  couple  of 

great,  unarmored,  liner-like  hulls,  engined  to  admit  of 

speeds  and  steaming  radii  such  as  will  permit  them 

AJJ  to   pursue   or   run   away  from   any 

IMAGINATIVE     armored  craft  yet  built,  and  designed 

SPECTACLE  f()r 


aeroplane  launching.  Conceive  them  provided  with 
storage  room  for  hundreds  of  demountable  aeroplanes, 
with  fuel,  repair  facilities,  and  explosives,  and  with 
housing  for  a  regiment  or  two  of  expert  air  navi- 
gators. Then  picture  the  terribly  one-sided  engage- 
ment that  will  ensue  —  the  thousands  of  tons  and 
millions  of  dollars'  worth  of  cunningly-fashioned 


38  VEHICLES  OF  THE  AIR 

mechanism  all  but  impotent  against  the  unremitted, 
harrying,  and  reinforced  attacks  from  aloft,  and 
unable  either  to  escape  from  or  give  chase  to  the 
enemy 's  floating  bases  of  supplies,  which,  ever  warned 
and  convoyed  by  their  aerial  supports,  will  unreach- 
ably  maneuver  out  of  gun  range,  picking  up  from  the 
water,  reprovisioning,  remanning,  launching  and 
relaunching  their  winged  messengers  of  death  until 
the  cold  waters  close  over  the  costly  armada  of  some 
nation  that  has  refused  to  profit  by  the  lessons  of 
progress. 

The  question  of  aerial  travel  over  water  is  one  of 

particular  significances.    Water  areas,  in  common  with 

the    atmosphere,    possess    a    quality 

™>  TrrAnrc,,       that  does  not  pertain  to  land  —  the 

OVER  WATER  , .  _  .  _  .  _, 

quality  of  uniformity.  The  conse- 
quence is  that  just  so  soon  as  means  are  devised  for 
launching  aeroplanes  over  water,  by  the  use  of  hydro- 
plane under  surfaces,  boat  convoys  (as  suggested  in 
the  preceding  paragraph),  or  any  other  serviceable 
expedient,  the  way  is  at  once  opened  to  the  establish- 
ment of  transaquatic  mail  lines  utilizing  craft  pro- 
vided with  hull-like  floats  and  made  capable  of  flying 
with  almost  perfect  safety  just  above  the  wave  crests. 
Indeed,  it  is  quite  to  be  anticipated  that  the  institu- 
tion of  some  such  service  may  constitute  the  first 
serious  commercial  exploitation  of  the  aeroplane.  A 
special  incentive  to  experiment  in  this  direction  is 
the  low  speed  of  even  the  fastest  present  water  travel, 
by  contrast  affording  to  the  flying  machine  an  advan- 
tage that  it  does  not  yet  possess  in  comparison  with  the 
higher  speeds  of  land  travel.  The  still  unsettled  ques- 
tions of  flying  radius  and  motor  reliability  can  be  at 
the  outset  tentatively  evaded  by  establishing  the  first 


INTRODUCTION  39 

services  over  the  shorter  distances,  or  by  stationing 
patrol  boats  with  fuel  supplies  at  necessary  intervals. 

It  is  an  irresistible  conclusion  that  the  practical 
utility  of  the  flying  machine  is  no  longer  to  be 
doubted.  The  only  questions  are 
those  of  the  exact  methods  of  realiz- 
ing these  utilities,  and  the  extent  of  their  applica- 
tion when  realized.  People  begin  to  see  that 
it  is  absurd  to  characterize  as  impossible  what 
has  been  long  accomplished.  The  bird  flies,  and  there 
is  nothing  occult  about  either  the  mechanism  of  the 
bird  or  the  laws  of  its  operation.  Not  even  the  soaring 
feats  of  the  bird  violate  any  of  the  laws  of  aerody- 
namics or  the  law  of  the  conservation  of  energy,  how- 
ever they  may  scandalize  some  pedantic  conceptions 
of  these  laws.  Difficulties  are  no  greater  than  the 
knowledge  required  to  surmount  them,  and  knowledge 
is  accumulating  hour  by  hour.  The  time  is  arriving 
when  it  will  be  no  more  difficult  to  maneuver  a  flying 
machine  than  it  is  to  ride  a  bicycle.  Both  are  dis- 
tinctly mechanical  inventions,  both  tend  unfailingly  to 
develop  from  inferior  to  superior  forms,  and  both 
have  had  to  encounter  various  skepticisms. 

Here  to  digress  for  a  moment — let  the  doubter  just 
consider  this  case  of  the  bicycle,  less  as  an  analogy  in 
mechanism  than  an  analogy  in  mental  attitudes.  Think 
of  a  "trained  engineer"  or  "conservative  business 
man"  of  a  few  years  ago  confronted  with  a  modern 
"safety",  exhibited  with  the  assertion  that  here  was  a 
vehicle  of  perfectly  practical  utilities,  inexpensive  to 
build  and  operate,  capable  of  considerable  speeds  under 
an  ordinarily  vigorous  rider,  and  perfectly  suit- 
able for  the  use  of  old  people  and  children  under  ordi- 
nary traffic  conditions.  Fancy  the  derision  —  the  criti- 


40  VEHICLES  OF  THE  AIR 

cism  that  would  be  leveled  at  the  pneumatic  tires,  the 
strictures  that  would  be  visited  upon  the  light  construc- 
tion, and,  above  all,  the  ridicule  that  would  be  heaped 
upon  the  proposition  of  requiring  from  ordinary  people 
the  balancing  instinct  of  the  acrobat  —  then,  perhaps, 
some  appreciation  will  be  had  of  the  way  most  present- 
day  opinions  on  aeronautics  will  fit  conditions  five 
years  from  now. 

And  if  all  this  insistence  brings  the  reader  to  some 
belief  that  possibly,  after  all,  this  epic  development  in 
transportation  is  upon  us,  what  of  the  changes  it  must 
involve — the  far-reaching  influences  it  must  inevitably 
exert  in  all  possible  fields  of  human  thought  and 
activity?  Ponder  the  romance  of  it  —  the  certainty 
that  it  must  completely  reorganize  more  than  one  fun- 
damental factor  of  the  present  social  order.  And 
believe — as  one  must  unless  lost  to  all  optimism  and 
faith — that  even  present  ills  work  for  ultimate  good, 
and  inquire  what  it  will  mean  to  live  under  skies 
thronged  with  aerial  fleets,  to  live  in  a  world  from 
which  the  artificial  barriers  of  national  boundaries  and 
the  natural  barriers  of  physical  characteristics  are  by 
advancing  intelligence  erased  past  re-establishment. 

What  must  be  the  result  when,  with  a  means  of 
travel  limited  neither  by  difficulties  of  topography  nor 
by  the  shores  of  the  seas,  lending  itself  perfectly  to 
individual  use  but  not  at  all  to  the  uses  of  monopoly, 
and  not  confined  to  the  narrownesses  of  specially  built 
highways,  the  greatest  freedom  the  individual  can 
possess — the  freedom  of  travel  far  and  wide  at  will — 
is  vastly  enhanced  by  the  vehicles  of  the  skies,  vehicles 
that  will  prove  cheaper  to  own,  maintain,  and  operate 
than  any  other  vehicles  that  have  ever  existed ! 

Travel  on  land  will  be  reduced  to  the  extent  that  it 


INTRODUCTION  41 

is  slow,  inefficient,  expensive,  and  inflexible.  Travel 
on  water  will  become  a  mere  adjunct  to  that  of  the  air. 
The  world  will  be  narrowed  by  the  speeds  attained. 
Tariff  and  exclusion  laws  will  be  annulled  through  the 
sheer  impossibility  of  their  enforcement.  And  the 
skies  will  be  as  thronged  with  the  craft  of  man's  devis- 
ing as  they  are  today  with  the  fowl  of  the  air. 

Throughout  the  territories  of  every  nation  of  the 
earth  there  will  appear  the  leveled,  circular,  landing 
areas,  perhaps  provided  with  strange-appearing  start- 
ing devices  and  probably  bordered  with  low,  capacious, 
shed-like  housings.  Automobiles  will  be  at  hand  to 
afford  rapid  transportation  to  the  business  centers  of 
adjoining  communities. 

There  will  develop  a  technique  and  a  language  of 
aerial  navigation,  and  experts  will  become  skilled  in 
contending  with  the  perversity  of  special  mechanisms, 
in  starting  and  landing  under  difficult  circumstances, 
in  battling  with  fog  and  rain  and  storm,  in  taking 
advantage  of  air  currents  at  different  levels,  and  in 
seeking  out  the  lanes  of  the  atmosphere  in  which  to 
add  to  their  speed  the  sweep  of  the  trade  winds. 

And  over  all  will  soar  with  the  ease  of  the  gull  or 
drive  with  the  speed  of  the  whirlwind,  the  myriad 
ships  of  the  air,  transforming  the  face  of  the  heavens. 
Of  many  sizes  and  at  many  altitudes,  midgets  and  levi- 
athans, close  to  the  earth  and  up  in  the  clouds — in  the 
days  the  shadows  of  their  wings  will  speed  over  every 
corner  of  all  the  lands  and  seas,  and  in  the  nights  of 
that  future  time  the  eye-like  gleams  of  their  search- 
lights will  mingle  to  the  uttermost  ends  of  the  earth, 
beacons  of  science  and  romance  and  progress  and 
brotherhood  VICTOE  LouOHEED_ 

CHICAGO,  November,  1909. 


CHAPTER  ONE 

THE  ATMOSPHERE 

At  least  a  brief  consideration  of  the  properties 
and  phenomena  of  the  atmosphere,  as  the  medium 
through  which  all  aerial  vehicles  must  travel  and 
from  which  they  must  derive  their  support,  has  a 
logical  place  in  a  work  of  this  character. 

EXTENT 

The  extent  of  the  gaseous  envelope  that  sur- 
rounds the  earth  is  a  subject  that  has  been  much 
investigated  by  physicists.  Knowing  the  weight 
of  the  air,  the  area  of  the  earth's  surface,  and  the 
approximate  mass  of  the  earth,  it  is  not  especially 
difficult  to  compute  the  total  weight  of  the  atmos- 
phere, which  is  found  to  be  abouty^-o-^-^nnj-  of  that 
of  the  rest  of  the  earth. 

Determination  of  the  height  of  the  atmosphere 
is  a  more  difficult  problem,  whether  it  be  attempted 
by  purely  mathematical  methods  or  reasoned  more 
or  less  empirically  from  such  observations  as  are 
available.  Were  the  air  of  uniform  density  from 
the  earth's  surface  to  its  limit  of  height  it  can  be 
easily  demonstrated  that  this  upper  limit  (termed 
by  scientists  the  "height  of  the  homogeneous  at- 
mosphere") would  be  at  an  altitude  of  about  26,166 
feet — lower  than  the  highest  mountain  tops — but 

43 


44  VEHICLES  OF  THE  AIR 

since  the  air  decreases  in  density  at  an  increasing 
ratio  as  the  pressure  due  to  air  above  grows  less 
with  each  increase  in  height,  until  the  atmosphere 
attenuates  by  imperceptible  graduations  into  a 
perfect  vacuum,  no  known  calculated  solution  of 
its  ultimate  height  can  be  closely  depended  upon. 

The  greatest  heights  above  sea  level  to  which 
man  has  actually  ascended  in  the  atmosphere  have 
been  reached  with  balloons,  Glaisher  and  Coxwell 
(see  Page  74)  having  attained  a  probable  height 
of  29,520  feet,  while  Berson  and  Sirring  (see  Page 
75)  undoubtedly  reached  an  altitude  of  35,400  feet. 

The  atmosphere  has  been  explored  to  much 
greater  heights  by  " sounding  balloons"  (see  Page 
75),  the  greatest  height  on  record  having  been 
reached  by  a  balloon  of  this  type  released  from 
TJccle,  Belgium,  on  November  5,  1908.  As  shown 
by  self-registering  instruments  attached  to  this 
balloon,  it  rose  to  a  height  of  29,040  meters  (95,275 
feet),  over  eighteen  miles. 

Estimates  based  on  the  calculated  heights  of 
meteors  at  the  times  when  they  commence  to  be- 
come luminous  from  friction  with  the  earth's  at- 
mosphere have  been  held  to  indicate  that  this  must 
extend,  in  an  exceedingly  tenuous  state,  to  a  height 
of  200  miles.  Other  authorities  contend  that  the 
extreme  upper  limit  cannot  be  over  100  miles  high. 
In  any  case,  it  is  an  obvious  deduction  from  the 
barometric  pressures  recorded  at  great  heights 
(see  Page  56)  that  |  of  the  whole  atmosphere  is 
below  30,000  feet,  TV  below  43,000  feet,  and 
Kr  below  95,275  feet. 


THE  ATMOSPHERE  45 

PROPERTIES  AND  CHARACTERISTICS 

The  atmosphere  being  chiefly  composed  of  sev- 
eral common  forms  of  matter,  its  principal  phys- 
ical properties  and  characteristics  have  been  well 
investigated. 

WEIGHT 

According  to  Regnault,  air  at  sea  level,  freed 
absolutely  from  water  vapor,  carbon  dioxid,  and 
ammonia,  weighs  .0012932  grams  to  the  cubic  cen- 
timeter at  zero  Centigrade,  under  a  pressure  of 
760  millimeters  of  mercury  in  the  latitude  of  Paris 
(48°  50'  K),  and  at  a  height  of  60  meters  above 
sea  level.  In  English  equivalents  this  is  approxi- 
mately equal  to  .080681  pound  to  the  cubic  foot — 
or  12.384  cubic  feet  to  the  pound — at  sea  level  in 
the  latitude  of  Washington,  D.  0.  Ordinarily,  not 
freed  from  water  vapor  and  other  impurities,  air 
at  sea  level,  at  32°  F.,  can  be  taken  to  weigh  very 
close  to  .080728  pound  to  the  cubic  foot. 

At  any  height  above  sea  level  a  given  volume 
of  the  atmosphere  weighs  an  amount  less  than  a 
similar  volume  at  sea  level  in  exact  proportion  to 
the  difference  in  barometric  pressure,  other  con- 
ditions being  equal.  Thus,  at  the  29,000  feet 
reached  in  the  Coxwell  and  Glaisher  balloon  ascent 
the  weight  of  the  air  was  only  .052171  pound  to  the 
cubic  foot. 

The  weight  of  the  air  is  an  important  consid- 
eration in  the  design  of  aerial  vehicles,  particu- 
larly in  the  case  of  lighter-than-air  constructions, 


46  VEHICLES  OF  THE  AIR 

since  these  are  enabled  to  float  only  by  being 
lighter  than  the  volume  of  air  they  displace.  With 
heavier-than-air  machines  the  weight  of  the  appa- 
ratus is  sustained  by  the  quantity  of  air  acted 
upon,  varying  with  area  of  surfaces,  rapidity  of 
the  action,  and  mass  of  the  air  affected. 

COMPOSITION 

Air  consists  chiefly  of  oxygen  and  nitrogen 
mechanically  admixed  (not  chemically  combined) 
in  the  proportion  of  about  21  volumes  of  oxygen 
to  79  volumes  of  nitrogen  (by  weight  the  propor- 
tions are  23.16  units  of  oxygen  to  76.77  of  nitro- 
gen). In  addition  to  these  principal  ingredients 
air  carries  minute  quantities  of  many  other  con- 
stituents, some  of  which  appear  in  the  constant 
proportions  indicative  of  normal  components, 
while  others  are  variable  with  locality  and 
circumstance. 

Among  the  more  evident  of  these  minor  con- 
stituents of  the  atmosphere  are  water  vapor,  car- 
bon dioxid,  ammonia,  nitric  acid,  argon,  helium, 
neon,  krypton,  and  ozone,  besides  quantities  of 
dust,  germs,  and  other  minute  solid  particles  held 
in  suspension.  The  water  vapor  may  represent  as 
much  as  2^  parts  by  weight  of  saturated  warm 
air,  but  ordinarily  the  quantity  is  much  less.  The 
carbon-dioxid  content  varies  from  .0043  in  the 
country  to  as  much  as  .07  or  even  .1  of  the  whole 
weight  of  the  air  in  cities.  This  gas,  which  is  pro- 
duced in  the  lungs  of  all  animals,  from  which  it  is 


TEE  ATMOSPHERE  47 

constantly  given  off  as  a  waste  product  of  the  con- 
tinuous oxidation  of  the  blood  that  is  essential  to 
life,  to  the  vegetable  kingdom  bears  the  relation 
of  a  food,  thus  beautifully  disclosing  the  wonderful 
adaptation  of  all  natural  phenomena  to  interlink 
with  one  another.  For  in  the  leaves  of  all  plants 
there  constantly  goes  on  a  mysterious  absorption 
and  fixation  of  the  carbon  from  the  carbon  dioxid 
of  the  atmosphere,  apparently  by  some  not  under- 
stood action  of  the  green  chlorophyl  they  contain, 
while  the  oxygen  thus  freed  from  its  combination 
is  in  this  case  the  waste  product. 

Argon  constitutes  about  .01  of  air.  The  total 
amount  of  ammonia  and  other  less  important 
gases  is  probably  less  than  .01  in  the  lower  atmos- 
phere, though  there  are  reasons  for  supposing 
some  of  these  gases  to  be  more  abundant  above. 
The  ammonia  in  air  is  generally  stated  as  amount- 
ing to  about  .000006  of  the  total  weight,  while  neon 
is  present  to  the  extent  of  about  .00001.  Both 
argon  and  helium  have  been  determined  to  exist 
at  all  heights  up  to  46,000  feet,  but  above  this 
height  no  helium  has  been  detected.  Ozone,  which 
is  an  allotropic  form  of  oxygen,  varies  from  none 
in  cities  to  .0000015  in  the  country,  and  is  more 
abundant  in  summer,  especially  during  thunder- 
storms and  high  winds.  The  amount  of  dust  in 
the  air  is  much  the  greatest  in  the  lower  strata  of 
the  atmosphere,  to  which  it  is  so  closely  confined 
that  balloonists  are  frequently  able  to  discern 
definite  dust  levels  at  certain  heights. 


48  VEHICLES  OF  THE  AIR 

COLOR  AND  TRANSPARENCE 

Though  in  small  quantities  air  is  without  any 
color  that  can  be  perceived,  the  fact  that  distant 
objects  seen  through  it  acquire  a  blue  tinge,  which 
also  appears  as  the  color  of  the  sky,  makes  it  evi- 
dent that  even  the  smallest  quantity  of  air  must 
faintly  possess  this  hue. 

While  commonly  regarded  as  perfectly  trans- 
parent, air  nevertheless  offers  considerable  ob- 
struction to  the  passage  of  light  rays  and  to  vision. 
Indeed,  were  the  atmosphere  in  undiminishing 
density  to  extend  to  any  great  height  it  is  a  safe 
conclusion  that  its  presence  would  prevent  our 
seeing  even  the  brightest  of  the  heavenly  bodies. 
As  it  is,  the  whole  amount  of  air  above  the  earth 
being  only  equivalent  to  26,166  feet  of  air  at  sea- 
level  density,  it  offers  more  obstruction  to  vision 
in  a  lateral  direction  than  in  the  vertical — a  fact 
that  becomes  very  apparent  when  it  is  attempted 
to  make  out  distant  details  from  a  mountain  top 
or  balloon,  affording  an  outlook  of  many  miles 
in  a  horizontal  direction.  Weight  for  weight,  air 
is  little  more  transparent  than  glass  or  water,  30 
feet  of  the  former  and  18  feet  of  the  latter  being 
equivalent  to  the  entire  height  of  the  atmosphere 
and  offering  little  more  obstruction  to  vision,  espe- 
cially when  compared  with  air  containing  much 
dust  or  water  vapor. 

AIR  AT  BEST 

Air  in  a  state  of  rest,  subjected  to  any  given 
but  unvarying  conditions  of  pressure,  temperature, 


THE  ATMOSPHERE  49 

and  composition,  presents  comparatively  few  and 
simple  problems.  Of  its  static  properties,  the 
most  important  are  its  compressibility,  those  re- 
lating to  the  effects  of  temperature,  and  those 
relating  to  its  phenomena  of  liquefaction  and 
solidification. 

COMPEESSIBILITY 

Air  in  common  with  all  other  gases  has  the 
quality  of  compressibility — a  quality  not  measur- 
ably possessed  by  most  liquids.  For  this  reason  its 
volume  is  always  proportionate  to  the  pressure 
upon  it,  it  expanding  with  every  reduction  in  pres- 
sure and  occupying  less  space  with  every  increase. 
Through  a  considerable  range  of  pressures  the 
space  occupied  is  almost  directly  proportionate  to 
the  pressure — a  doubling  of  the  pressure  reducing 
the  volume  by  one-half,  etc.  Air  cannot  be  com- 
pressed without  the  work  expended  appearing  in 
the  form  of  a  rise  in  temperature,  and,  conversely, 
allowing  compressed  air  to  expand  always  results 
in  a  lowering  of  temperature. 

EFFECT  OF  TEMFEBATTJEE 

Heating  or  cooling  of  air  causes  it  to  expand  or 
contract.  Through  a  considerable  range  of  the  com- 
moner temperatures  such  expansion  or  contraction 
is  closely  proportionate  to  the  amount  of  change 
in  temperature.  This  property  is  taken  advantage 
of  in  hot-air  balloons,  as  explained  on  Page  97. 
Heating  air  that  is  confined  results  in  an  increase 
of  pressure,  and  cooling  compressed  air  results  in 
a  decrease  of  pressure. 


50  VEHICLES  OF  THE  AIR 

LIQUEFACTION  AND  SOLIDIFICATION 

Almost  every  known  form  of  matter,  whether 
normally  appearing  as  a  solid,  liquid,  or  gas,  can 
by  sufficient  change  in  the  conditions  of  tempera- 
ture and  pressure  be  made  to  assume  any  of  these 
three  conditions.  Thus  the  hardest  rocks  and  the 
strongest  metals  can  be  melted  into  liquids  and 
volatilized  into  gases,  while  practically  all  known 
liquids  can  be  solidified — as  in  the  familiar  case 
of  the  freezing  of  water.  Likewise,  the  lightest 
gases,  when  subjected  to  sufficient  cold  and  pres- 
sure, assume  first  a  liquid  and  then  a  solid  form. 
Air  is  no  exception  to  this  rule,  becoming  a  liquid 
at — 220°  Fahrenheit  under  a  pressure  of  574 
pounds  to  the  square  inch — or  less,  if  the  tempera- 
ture be  lower.  Further  cooling  causes  it  to  become 
solid,  though  the  temperature  required  to  pro- 
duce this  condition  is  so  low  that  it  can  be  at- 
tained only  with  the  greatest  difficulty. 

Liquid  air,  because  of  its  compact  form  as  a 
source  of  oxygen,  and  its  expansion  into  the  gas- 
eous form  at  high  pressure  upon  exposure  to  or- 
dinary atmosphere  temperatures,  often  has  been 
proposed  as  a  source  of  stored  energy  for  motors, 
but  so  far  no  such  application  has  proved  suc- 
cessful. 

AIR  IN  MOTION 

Air  in  motion  possesses  properties  that  are 
very  little  understood,  the  laws  of  its  dynamic 
actions  and  reactions  not  having  been  gener- 
ally investigated  or  formulated.  Particularly  with 


THE  ATMOSPHERE  51 

reference  to  the  operation  of  heavier-than-air  ma- 
chines is  this  the  case.  Indeed,  more  than  one  of 
the  world's  foremost  physicists,  even  in  compara- 
tively recent  years,  has  positively  declared  aerial 
navigation  to  be  impossible,  basing  his  conclusions 
upon  difficulties  encountered  in  reconciling  the 
idea  of  man  flight  with  established  hypotheses 
of  aerodynamics.  Air,  possessing  almost  perfect 
elasticity  in  addition  to  its  weight,  fluidity,  and 
other  qualities,  cannot  be  set  in  any  but  the  most 
simple  movements  without  occasioning  a  multi- 
tude of  resultants  that  are  so  utterly  complex  and 
involved  as  almost  to  defy  analysis.  The  result  is 
that  even  such  comparatively  simple  phenomena 
as  those  of  the  movement  of  air  in  pipes  and  in 
jets  are  only  understood  in  a  general  way,  while 
the  work  of  most  investigators  of  flight  problems 
has  had  to  be  almost  purely  empirical,  or,  when 
mathematical,  has  been  unsuccessful.  The  one 
conspicuous  exception  with  which  the  writer  is 
familiar  is  found  in  the  investigations  and  ex- 
periments of  Professor  Montgomery,  whose  con- 
clusions are  outlined  in  the  article  printed  in 
Chapter  4. 

Of  the  dynamic  properties  of  air,  the  most  im- 
portant from  present  standpoints  are  its  inertia, 
elasticity,  and  viscosity. 

INERTIA 

Air,  in  common  with  all  other  matter  having 
weight,  exhibits  the  various  phenomena  of  inertia, 
which  may  be  defined  as  the  tendency  of  a  mass  to 


52  VEHICLES  OF  THE  AIR 

remain  at  rest,  or  to  continue  in  uniform  motion  in 
a  straight  line,  until  acted  upon  by  some  disturb- 
ing or  retarding  force.  Naturally,  air  being  much 
lighter  than  solid  and  liquid  forms  of  matter,  its 
inertia  is  less  marked  than  in  the  case  of  heavier 
substances.  But  that  under  favorable  conditions 
this  is  a  factor  to  reckon  with  is  abundantly  proved 
throughout  a  great  range  of  natural  phenomena, 
from  the  flight  of  birds  to  the  extraordinary  vaga- 
ries of  cyclone  action.  In  fact,  as  one  great  in- 
vestigator has  tersely  expressed  a  profound  truth 
in  form  to  be  appreciated  by  the  man  in  the  street, 
"the  air  is  hard  enough  if  it  is  hit  fast  enough." 

ELASTICITY 

The  property  of  elasticity  is  one  of  the  funda- 
mental qualities  that  distinguish  air  and  other 
gases  from  liquids.  Air  and  other  gases  are  in 
fact  the  only  perfectly  elastic  substances  known — 
that  is,  the  only  substances  that  will  withstand 
compression  to  an  indefinite  extent  and  for  in- 
definite periods  without  in  the  slightest  degree 
losing  their  ability  fully  to  recover  the  original 
volume.  Gases  compressed  under  thousands  and 
even  hundreds  of  thousands  of  pounds  to  the 
square  inch,  for  no  matter  how  long  a  period,  in- 
stantly and  unfailingly  expand  to  any  extent  per- 
mitted by  release  of  the  pressure. 

It  is  to  a  great  extent  this  property  that,  under 
favorable  conditions,  makes  for  the  high  efficiencies 
realized  with  suitably-designed  mechanisms  for 
operating  on  masses  of  air  see  Page  255). 


THE  ATMOSPHERE  53 

VISCOSITY 

Viscosity  is  a  property  of  fluids  closely  com- 
parable to  the  cohesion  of  solids  and  may  be  de- 
fined as  the  tendency  of  the  molecules  to  occasion 
friction  when  driven  against  or  past  one  another. 
The  viscosity  of  air  is  often  stated  to  be  much 
higher  than  that  of  water  (not  per  unit  of  volume, 
but  per  unit  of  weight),  but  there  is  reason  for 
doubting  the  soundness  of  this  conclusion.  How- 
ever, it  is  at  least  true  that  air  possesses  viscosity, 
and  that  this  sets  up  increasing  resistances  to 
movement  as  the  speed  of  the  movement  rises. 
The  question  of  skin  friction  on  aeroplane  and 
propeller  surfaces  is  closely  related  to  that  of  the 
viscosity  of  air. 

METEOROLOGY 

The  matters  of  climatic  conditions,  storm 
phenomena,  and  temperature,  and  barometric  and 
electrical  conditions  in  the  atmosphere  must  all, 
in  the  nature  of  things,  be  of  the  utmost  interest 
to  both  present  and  future  air  navigators. 

Meteorological  conditions  may  be  broadly 
grouped  in  two  classes — the  first  comprised  of  con- 
ditions of  a  primary  or  static  character,  and  there- 
fore not  directly  inconsistent  with  fair  weather, 
while  the  second  class  includes  such  meteorological 
phenomena  as  are  directly  related  to  winds  and 
storms. 

Generally  speaking,  there  are  three  funda- 
mental or  primary  changes  to  be  noted  in  the  at- 


54  VEHICLES  OF  THE  AIR 

mosphere  in  a  given  period  in  any  locality — 
changes  in  temperature,  changes  in  barometric 
pressure,  and  changes  in  humidity.  Secondary  ef- 
fects, usually  rather  definitely  resultant  from  the 
foregoing,  are  the  condensation  of  moisture  and  its 
precipitation — in  the  form  of  rain,  snow,  or  hail — 
and  the  movement  of  the  air  in  the  form  of  winds. 

TEMPEKATUKE 

Besides  the  seasonal  variations  in  temperature, 
which  vary  greatly  with  locality,  there  is  the  re- 
markably uniform  lowering  of  temperature  with 
increase  of  height,  the  atmosphere  being  warmest 
at  or  near  the  surface  at  sea  level  and  progressive- 
ly colder  at  greater  altitudes,  as  is  evident  in  the 
phenomenon  of  perpetual  snow  on  high  mountains, 
even  in  warm  climates. 

Observations  with  sounding  balloons  have  dis- 
covered temperatures  lower  than  — 100°  F.  at  great 
heights,  with  — 50°  commonly  prevailing,  even  in 
summer.  The  lowest  temperature  ever  recorded 
at  the  earth's  surface  is  — 90°  F.,  observed  in  Si- 
beria— this  degree  of  cold  exceeding  any  that  has 
been  recorded  elsewhere  on  the  surface,  even  in 
polar  exploration.  At  the  other  end  of  the  range 
are  temperatures  of  about  140°  above  zero  Fahren- 
heit, noted  in  India,  the  Sahara,  the  southwestern 
United  States,  Australia,  and  elsewhere  in  the 
desert  and  equatorial  regions  of  the  world. 

The  following  two  tables  of  sounding-balloon 
records  will  be  of  interest: 


THE  ATMOSPHERE  55 

FROM  SAINT  LOUIS,  MAY  6,  1906       FROM  SAINT  LOUIS,  MAY  10,  1906 

HEIGHT  ABOVE  HEIGHT  ABOVE 

SEA  LEVEL                   TEMPERATURE  SEA  LEVEL                   TEMPERATURE 

623    feet 57.2°  F.  623  feet 68.0°  F. 

3,281    feet 46.4°  F.  3,281  feet 59.0°  F. 

6,562    feet 81.2°  F.  6,562  feet 46.4°  F. 

9,843    feet 21.2°  F.  9,843  feet 37.2°  F. 

13,123    feet 15.8°  F.  13,123  feet 21.2°  F. 

16,404    feet 17.6°  F.  16,404  feet —  6.8°  P. 

19685    feet 5.0°  F.  19,685  feet —  2.2°  F. 

32,808    feet — 52.6°  F.  22,966  feet — 26.6°  F. 

26,247    feet —29.2°  F.  26,247  feet —32.8°  F. 

29,527    feet — 40.0°  F.  29,527  feet — 45.4°  F. 

32,808    feet — 52.6°  F.  32,808  feet — 59.0°  F. 

36,089    feet — 50.8°  F.  36,089  feet — 76.0°  F. 

39,370    feet — 49.0°  F.  39,370  feet — 70.6°  F. 

42,651    feet — 54.4°  F.  42,651  feet — 67.0°  F. 

45,932    feet — 56.2°  F.  45,932  feet — 70.6°  F. 

49,212    feet — 59.0°  P.  49,212  feet — 72.4°  P. 

52,893  feet —68.8°  F. 

54,298  feet —67.0°  F. 

A  remarkable  feature  well  shown  in  the  above 
is  the  " permanent  inversion  layer",  or  isothermal 
stratum,  of  the  upper  atmosphere,  it  being  noted 
that  at  from  33,000  to  49,000  feet— beginning  just 
higher  than  the  tops  of  the  highest  mountains — a 
minimum  temperature  is  reached,  after  which  there 
tends  to  be  a  slight  but  fairly  regular  rise.  This 
change  has  been  discovered  to  exist  all  over  the 
world — in  both  the  tropical  and  temperate  zones, 
near  the  arctic  circle,  and  over  the  Atlantic  ocean. 
In  the  record  ascent  of  the  sounding  balloon  from 
Uccle  (see  Page  44)  the  lowest  temperature 
registered  was  —108.6°  F.,  at  42,323  feet.  At 
95,275  feet,  the  greatest  altitude  reached,  the  tem- 
perature had  risen  to  — 82.12°  F. 

In  the  Berson  and  Sirring  ascent,  on  December 
4,  1894,  the  lowest  temperature— at  28,750  feet- 
was  — 54°  F.  At  the  start  in  Berlin  the  tempera- 
ture was  37°  F. 


56  VEHICLES  OF  THE  AIR 

BAROMETRIC  PRESSURE 

The  weight  of  the  atmosphere,  as  shown  by  the 
barometric  pressure,  varies  with  height,  tempera- 
ture, and  latitude.  As  is  elsewhere  explained 
herein,  by  far  the  most  considerable  variations  are 
those  due  to  height,  for  which  reason  a  high-grade 
aneroid  barometer  constitutes  a  very  accurate 
means  of  estimating  altitude. 

At  sea  level,  under  normal  conditions,  the  baro- 
metric pressure  is  almost  exactly  14.7  pounds  to 
the  square  inch.  At  great  heights  it  is  much  less, 
as,  for  example  in  the  Glaisher  and  Coxwell  ascent 
(see  Page  74). 

The  Uccle  sounding  balloon  recorded  a  pressure 
of  1.74  pounds  to  the  square  inch  at  42,240  feet, 
and  of  only  .2  pounds  to  the  square  inch  at  its 
greatest  height  of  95,275  feet. 

HUMIDITY 

Humidity  is  a  general  term  for  the  presence  of 
water  vapor  in  air,  but  in  the  more  restricted  and 
more  specific  scientific  sense  it  is  commonly  under- 
stood to  refer  to  the  percentage  of  saturation — that 
is  to  say,  to  the  proportion  that  the  amount  of 
moisture  actually  present  in  the  air  bears  to  the 
maximum  it  might  contain.  The  saturation  point 
varies  with  temperature — cold  air  being  capable  of 
holding  less  and  warm  air  more  water  vapor.  At 
a  temperature  of  about  90°  F.  a  cubic  foot  of 
saturated  air  will  contain  about  TV  ounce,  or 
about  TV  cubic  inch,  of  water.  Saturated  air 


THE  ATMOSPHERE  57 

cooled  to  a  lower  temperature  always  precipitates 
its  excess  of  water.  This  is  the  explanation  of  the 
condensed  moisture  that  is  often  precipitated  from 
the  air  on  the  outside  of  a  glass  of  cold  water,  or 
upon  any  other  cold  surface  in  warm  weather,  and 
it  has  most  important  bearings  upon  the  phe- 
nomena of  rain  and  snow  fall. 

The  moisture  in  the  air  is  chiefly  derived  by 
evaporation  from  water  areas  and  land  wetted  by 
rains  or  floods. 

CONDENSATION  OF  MOISTUEE 

This  always  occurs  when  the  atmosphere  is 
cooled  until  the  amount  of  water  present  in  it 
amounts  to  more  than  the  saturation  quantity  for 
the  given  temperature,  and  the  result  is  ordinarily 
a  precipitation  of  rain,  snow,  or  hail — though  it 
is  established  that  under  certain  conditions  mois- 
ture thus  precipitated  may  pass  into  vapor,  or  be 
frozen  in  exceedingly  minute  crystals,  and  so  re- 
tained in  suspension  in  the  form  of  clouds. 

WINDS 

Winds,  amounting  simply  to  more  or  less  rapid 
movement  of  portions  of  the  atmosphere  with  re- 
lation to  the  earth's  surface,  present  many  aspects 
of  interest  to  the  air  navigator,  and  are  worthy 
of  his  prof oundest  consideration. 

Atmospheric  movements  vary  in  direction, 
velocity,  and  duration,  and  in  the  presence  of 
ascending  or  descending  components,  and  are 
classified  according  to  their  velocity,  direction, 


58  VEHICLES  OF  THE  AIR 

and  duration  into  the  different  classes  of  storms 
and  winds. 

Winds  are  supposed  to  be  due  chiefly  to  varia- 
tions in  temperature,  though  they  are  affected  by 
tidal  movements  in  the  atmosphere  and  influenced 
by  the  earth's  rotation.  The  latter,  however,  can- 
not be  of  very  great  effect  because,  though  the 
equatorial  speed  of  rotation  is  over  1,000  miles  in 
hour,  everything  terrestrial  is  so  subjected  to  the 
earth's  attraction  that  it  must  be  moved  uniformly 
along  without  materially  lagging  behind,  as  might 
be  the  case  were  the  rotation  irregular  or  inter- 
mittent. 

Tidal  currents  in  the  air,  caused  by  the  attrac- 
tion of  the  sun  and  moon,  are  well  established  to 
exist,  but  because  of  the  comparatively  small  mass 
of  the  air  they  do  not  vary  the  barometric  pressure 
more  than  -gV  ounce  at  sea  level,  and  therefore 
cannot  be  of  any  considerable  effect  in  establishing 
or  controlling  winds. 

Changes  in  temperature  produce  effects  of 
much  greater  magnitude.  Air  heated  through  a 
range  of  50°  F,  is  dilated  about  one  tenth  of  its 
volume — with  corresponding  lightening  of  its 
weight  per  unit  of  volume.  The  result,  therefore, 
of  a  change  of  temperature  in  any  portion  of  the 
atmosphere  is  a  compression  or  attenuation  that 
can  be  relieved  only  by  a  flow  of  air  from  or  to  the 
locality  affected,  with  a  violence  proportionate  to 
the  suddenness  and  amount  of  the  temperature 
change  and  the  quantity  of  air  it  affects.  Also, 
air  being  lightened  by  heating,  heated  bodies  of  it 


TEE  ATMOSPHERE  59 

have  a  tendency  to  rise,  causing  an  upward  com- 
pression with  a  radial  inflow  from  all  surrounding 
places  to  occupy  the  spaces  thus  becoming  vacated. 
Again,  air  thus  caused  to  ascend  into  the  upper 
regions  of  the  atmosphere,  where,  as  has  been  ex- 
plained, conditions  of  the  most  intense  cold  prevail 
throughout  the  year,  becomes  cooled  and  thus  is 
turned  from  its  vertical  into  a  horizontal  and  final- 
ly a  descending  course. 

The  fact  that  a  rapid  fall  of  the  barometer — 
indicating  a  reduction  in  the  weight  of  the  air — 
almost  always  precedes  violent  winds,  seems  proof 
positive  of  the  soundness  of  the  accepted  theories 
of  wind  causation. 

There  are  two  principal  modes  of  heating  to 
which  the  atmosphere  is  subjected.  One  is  the 
regular  diurnal  heating  due  to  the  alternation  of 
day  and  night,  a  wave  of  heated  air  progressing 
around  the  world  with  the  sun  while  a  converse 
cool  wave  follows  the  night.  The  other  type  of 
heating  is  that  to  which  the  atmosphere  is  sub- 
jected over  great  areas  in  contact  with  the  earth — 
a  type  of  heating  that  becomes  particularly  mani- 
fest over  great  areas  of  prairie  or  desert  country 
in  summer. 

Coastal  Winds  are  common  along  almost  all 
seacoasts  and  even  along  the  shores  of  large  lakes. 
They  seem  distinctly  due  to  the  effects  of  tempera- 
ture, and,  commencing  with  a  light  breeze  from  the 
sea  in  the  morning  rise  to  a  stiff  wind  by  midday, 
subsiding  again  to  a  calm  by  evening.  Then,  as 
darkness  comes  on,  a  breeze  sets  in  from  the  land, 


60  VEHICLES  OF  THE  AIR 

reaching  its  maximum  velocity  sometime  in  the 
night,  and  thereafter  dying  down  towards  morn- 
ing. These  winds  are  rarely  felt  more  than  twenty 
miles  out  to  sea  or  inland,  and  investigation  with 
kites  and  balloons  has  shown  them  to  be  invariably 
accompanied  by  an  opposite  movement  of  the  air 
at  some  distance  above — usually  at  a  very 
moderate  height  (500  to  1,000  feet).  This,  besides 
proving  that  the  air  travels  in  a  complete  circuit, 
goes  a  long  way  towards  explaining  the  phe- 
nomenon, it  being  reasoned  that  as  the  air  is 
warmed  over  the  land  by  the  heat  of  the  day  it 
rises,  is  replaced  by  air  flowing  in  from  the  sea, 
and  then  flows  seaward  at  an  upper  level  because 
of  the  reduced  pressure  in  that  direction.  At  night 
the  land  is  more  quickly  affected  by  the  withdrawal 
of  the  sun's  rays,  so  now  the  ascending  current 
commences  over  the  sea,  with  a  sequence  of  results 
exactly  the  converse  of  the  foregoing. 

Trade  Winds,  so  called  because  of  the  de- 
pendence placed  in  them  by  navigators  of  sailing 
vessels,  are  always  in  the  same  direction  but  with 
seasonal  variations  in  the  areas  they  extend  over. 
They  are  due  to  cold  currents  flowing  in  from  the 
polar  regions  to  replace  the  warm  air  that  rises 
from  the  equatorial  regions  of  the  earth.  Normally, 
they  would  flow  directly  north  and  south  to  the 
equator,  but  the  influence  of  the  earth's  rotation 
and  the  configuration  of  the  land  and  water  areas 
in  the  northern  hemisphere  causes  them  gradually 
to  veer  about,  as  they  progressively  reach  latitudes 
where  the  peripheral  speed  of  the  earth's  surface 


THE  ATMOSPHERE  61 

is  higher,  until  they  flow  almost  directly  west,  but 
slightly  north  or  south  (constituting  the  "  north- 
east trade"  and  the  " southeast  trade").  The 
trade  winds  follow  the  sun  very  closely  in  their 
areal  variations.  Over  the  Atlantic,  for  example, 
they  come  farthest  south  in  February  and  go 
farthest  north  in  August,  the  northeast  trades 
blowing  between  7°  and  30°  north  latitude  and  the 
southeast  trades  blowing  between  3°  north  latitude 
and  25°  south  latitude.  Between  the  two  is  a 
region  of  calms,  from  3°  to  8°  wide,  which  goes  as 
far  north  as  11°  north  latitude  in  August  and  as  far 
south  as  1°  north  latitude  in  February. 

Above  the  trade  winds  there  are  well  estab- 
lished to  exist  return  currents,  blowing  in  the  op- 
posite directions.  In  high  latitudes  these  return 
currents  often  come  down  to  the  surface  and  pro- 
duce easterly  trade  winds. 

Cyclones,  Whirlwinds,  and  Tornadoes  are 
local  winds  of  terrific  violence  and  rotary 
character,  which  are  started  by  rapid  and  intense 
local  heating,  with  consequent  rapid  rising  of 
locally-heated  atmosphere — at  such  a  rate  that  the 
radial  inflow  of  adjoining  air  assumes  a  rotary 
movement  similar  to  that  of  water  in  draining  out 
through  a  hole  in  a  vessel.  The  vortex  of  the  storm 
is  at  the  center  of  this  rotation,  where  most  ter- 
rible wind  velocities  are  attained  if  their  frightful- 
ly-destructive effects  are  any  criterion.  For- 
tunately cyclones  are  usually  very  small  in  their 
areas  of  maximum  violence  and  are  of  compara- 
tively brief  duration. 


62  VEHICLES  OF  THE  AIR 

Ascending  Components  in  apparently  horizon- 
tal winds,  and  especially  in  those  blowing  over 
horizontal  surfaces,  have  occasioned  much  discus- 
sion and  speculation  by  students  of  aerial  naviga- 
tion because  of  the  supposed  bearing  upon  the  sus- 
tained soaring  flight  of  certain  birds.  Now,  though 
it  is  fairly  established  that  such  ascending  com- 
ponents exist,  it  seems  doubtful  whether  they  con- 
stitute the  essential  means  to  soaring  flight.  Never- 
theless, it  is  evident  that  indefinite  progress  in  a 
horizontal  direction  might  be  made  with  a  gliding 
machine,  were  the  air  continuously  rising.  Indeed, 
the  resulting  condition  might  be  likened  to  that  of 
a  vehicle  coasting  down  a  hill  that  rose  as  fast  or 
faster  than  the  vehicle  descended.  Rising  currents 
are  now  attributed  to  two  principal  causes — one, 
the  slant  of  irregular  country  over  which  winds 
may  blow,  and  the  other,  over  flat  country,  the  re- 
tarding friction  of  the  lower  strata  of  air  on  the 
surface. 

Another  class  of  rising  currents  is  that  due  to 
heating  of  the  air.  Chanute  is  authority  for  the 
statement  that  such  vertical  currents,  unaccom- 
panied by  adjacent  horizontal  currents,  may  flow 
as  fast  as  from  6  to  10  miles  an  hour. 

Wind  Velocities  vary  from  those  of  most  im- 
perceptible zephyrs  to  the  immeasurable  violence 
of  the  cyclone.  The  highest  winds  that  have  been 
successfully  recorded  by  anemometers  are  slightly 
in  excess  of  100  miles  an  hour,  this  rate  being 
briefly  reached  nearly  every  year,  for  example,  at 
the  weather  station  at  Point  Lobos,  California. 


TEE  ATMOSPHERE  63 

Ordinarily  wind  velocities  average  much  lower. 
In  650  different  daily  observations  of  wind  move- 
ment over  the  five  great  oceans,  taken  on  board  the 
"  Challenger"  during  a  3|  years'  cruise  that  ended 
in  May,  1876,  the  mean  hourly  wind  velocity  was 
17  miles.  In  552  observations  taken  on  land 
during  the  same  period  the  mean  hourly  velocity 
amounted  to  only  12-J-  miles. 

Wind  velocities  are  much  greater  at  high  alti- 
tudes than  lower  down.  Kite  experiments  in  a 
wind  of  22.1.  miles  an  hour  at  the  surface  have  on 
at  least  one  occasion  indicated  a  velocity  of  over 
130  miles  an  hour  at  a  great  height.*  Very  mod- 
erate heights  are  enough  to  cause  a  considerable 
difference,  and  observation  will  often  show  a  wind 
velocity  of  twice  that  at  the  ground,  at  a  height  of 
no  more  than  50  or  60  feet. 

Besides  to  major  changes  in  velocity  and  di- 
rection, winds  are  subject  to  a  multitude  of  minor 
variations  and  fluctuations,  almost  from  moment  to 
moment,  especially  in  proximity  to  terrestrial  ir- 
regularities, which  retard  and  deflect  them  and 
otherwise  interfere  with  their  free  sweep.  Record- 
ing instruments  show  that  such  fluctuations  are 
often  quite  incessant,  occuring  with  great  fre- 
quency and  throwing  the  air  into  billows  and 
whirls  and  irregularities — which  to  cope  with  safe- 
ly is  certainly  to  be  regarded  as  one  of  the  more 
serious  problems  of  aerial  navigation. 


*  It  is  to  be  borne  in  mind  that  at  very  great  altitudes  the  small 
weight  of  the  air  per  unit  of  volume  increases  its  mobility  and  reduces 
the  force  of  its  effects. 


64  VEHICLES  OF  THE  AIR 

ATMOSPHEEIC  ELECTRICITY 

The  presence  of  electrical  action  in  the  atmos- 
phere, due  to  the  accumulation  of  enormous  static 
charges  of  current  generated  presumably  by  fric- 
tion of  the  air  upon  itself,  accounts  for  the  various 
phenomena  of  lightning  and  thunderstorms.  To 
the  student  of  aerial  navigation  the  most  interest- 
ing aspect  of  these  phenomena  is  their  danger  from 
the  standpoint  of  the  balloonist,  it  being  well 
established  that  hydrogen  balloons  have  been  set 
on  fire  by  electrical  discharges,  often  of  otherwise 
quite  imperceptible  character. 


FIGURE  2. — A  corner  of  the  Aeronautical  Exhibition  held  in  the  Grand  Palais,  Paris, 
during  October,  1909.  The  small  decorated  balloon  in  the  background  is  a  reproduction  of 
the  original  Montgolfier  balloon  of  1783 — the  first  ever  made. 


A.— Double    (Silk).  B.— Double   (Silk). 


C. — Double    (Silk  and  Cotton) 


D. — Double   (Cotton). 


E. — Double   (Cotton). 


F. — Double    (Cotton). 


G. — Double    (Silk  and  Cotton). 


EL — Single  (Percale). 


I. — Double  (Percale). 


J. — Double  (Percale). 


Double    (Percale), 


L.—jKj.jbhs ;  f  I'e'rcele ) . 


M. — Double   (Percale). 


O.- — Double    (Percale). 


N. — Triple   (Percale). 


P. — Double   ( Percale ) . 


Q. — Double  (Percale). 


FiGDitE  7. — Texture  of  Modern  Balloon  Fabrics — Reproduced  Actual  Size.  Of  these,  A  is 
a  very  light  fabric  ;  B  is  similar  but  heavier  ;  C  is  the  material  of  the  Baldwin  government 
balloon  ;  D,  E,  and  F  are  heavy  fabrics  ;  G  is  similar  to  C,  but  heavier  ;  H  is  a  very  light 
fabric  for  sounding  balloons  ;  I  is  a  very  light  double  fabric,  used  in  the  Zeppelin  dirigibles  ; 
J  and  K  are  double  fabrics  with  the  layers  crossed  to  add  strength  ;  L  and  M  are  exceedingly 
heavy  double  fabrics,  for  semi-rigid  and  non-rigid  dirigibles ;  N  is  one  of  the  heaviest  balloon 
fabrics  used,  weighing  14 ^  ounces  to  the  square  yard;  and  O,  P,  and  Q  are  all  high-grade 
diagonal  fabrics  with  gray  rubber  to  retain  the  gas  and  red  surfaces  to  resist  sunlight. 


CHAPTER  TWO 

LIGHTER-THAN-AIR  MACHINES 

Though  as  a  vehicle  of  practical  utilities  it  is 
fast  losing  ground  in  comparison  with  the  develop- 
ing forms  of  heavier-than-air  fliers,  and  seems  con- 
demned by  insuperable  objections  inherent  in  its 
very  principle  of  operation,  the  lighter-than-air 
machine — the  balloon — was  nevertheless  the  first 
with  which  man  succeeded  in  sustaining  himself  in 
the  air  for  considerable  periods  of  time. 

Since  the  essential  feature  of  lighter-than-air 
craft  is  their  ability  to  float  in  the  air  much  as  a 
vessel  floats  in  the  water,  and  since  the  only  sub- 
stances that  even  approach  air  in  lightness  are 
also  gases,  it  follows  that  the  design  of  no  conceiv- 
able sort  of  lighter-than-air  machine  can  escape 
the  necessity  for  two  essential  elements — space  oc- 
cupied by  something  lighter  than  air,  and  an  envel- 
ope of  heavier-than-air  material  to  enclose  this 
space — with  the  relations  between  these  two  ele- 
ments so  proportioned  that  the  lifting  force  of 
the  gas  is  sufficient  to  overcome  the  weight  of  the 
envelope.  In  any  practical  air  craft,  to  the  weight 
of  these  primary  essentials  must  be  added  such 
further  weight  of  structure  as  may  be  considered 

65 


66  VEHICLES  OF  THE  AIR 

necessary  to  afford  passenger  or  cargo  accommo- 
dation, and  such  further  quantity  of  gas  as  may  be 
required  to  lift  such  passengers  or  cargo  as  it  may 
be  planned  to  carry. 

NON-DIEIGIBLE  BALLOONS 

The  most  elementary  type  of  balloon  is  that  de- 
signed for  mere  ascension  and  flotation  in  the  air, 
With  no  attempt  at  navigation  in  a  lateral  direction 
except  as  such  lateral  travel  may  result  from  fa- 
vorable winds.  It  was  a  very  early  suggestion  in 
the  history  of  the  balloon  that,  inasmuch  as  the 
direction  of  the  winds  frequently  varies  with  dif- 
ferences in  altitude,  upper  currents  often  flowing 
directly  contrary  to  those  near  the  surface,  sys- 
tematic prospecting  through  these  different  cur- 
rents by  control  of  height  might  result  in  control 
of  the  direction  of  travel.  Yet  in  the  hundreds  of 
attempts  made  to  work  something  practical  out  of 
this  idea,  nothing  of  real  value  has  developed. 

HISTORY 

If  somewhat  uninvestigated,  but  in  nowise  dis- 
credited Oriental  history  is  to  be  believed,  the 
invention  of  the  balloon  is  properly  to  be  ascribed 
to  that  inscrutable  people,  the  Chinese,  who,  ac- 
cording to  a  French  missionary  writing  in  1694, 
sent  up  a  balloon  in  celebration  of  the  corona- 
tion of  the  emperor  Fo-Kien,  at  Pekin,  in  1306. 
Furthermore,  this  ascension  is  stated  to  have  been 
only  the  carrying  out  of  an  established  custom, 
rather  than  the  first  ever  made  by  the  Chinese.  It 


LIGHTER-THAN-AIR  MACHINES  67 

is  not  recorded  whether  or  not  any  of  the  Chinese 
balloons  ever  carried  passengers. 

The  first  European  appreciation  of  the  prin- 
ciple by  which  a  balloon  is  made  to  ascend  appears 
to  have  been  due  to  a  Jesuit,  Francis  Lana,  who  in 
a  work  published  at  Brescia,  Italy,  in  1670,  pro- 
posed an  airship  sustained  by  four  hollow  copper 
vacuum  balls,  each  twenty-five  feet  in  diameter 
and  -^4^  inch  thick,  affording  a  total  ascensional 
force  of  about  2,650  pounds,  of  which  some  1,620 
pounds  would  be  the  weight  of  the  copper  shells, 
leaving  1,030  pounds  for  the  weight  of  the  car,  pas- 
sengers, etc.  The  difficulty  of  securing  sufficient 
strength  to  withstand  the  pressure  of  the  atmos- 
phere Lana  assumed  would  be  met  by  the  domed 
form  of  the  surface,  but  in  view  of  the  fact  that 
the  total  pressure  on  each  sphere  would  figure  over 
4,000,000  pounds,  the  possibility  of  resisting  it 
with  so  thin  a  shell  still  remains  to  be  demon- 
strated. 

In  1766  Cavendish  made  public  his  estimations 
of  the  weight  of  hydrogen,  immediately  following 
which  Dr.  Black,  of  Edinburgh,  made  a  calf-gut 
balloon  which,  however,  proved  to  be  too  heavy  for 
sustention  by  the  hydrogen  it  could  contain.  A 
few  years  later,  Tiberius  Cavallo,  to  whom  a  simi- 
lar idea  occurred,  found  bladders  to  be  too  heavy 
and  paper  too  permeable,  but  he  did  succeed  in 
inflating  soap  bubbles  with  hydrogen  in  1782,  with 
the  result  that  they  floated  upwards  until  they 
burst. 

It  is  a  somewhat  remarkable  coincidence  that 


68  VEHICLES  OF  THE  AIR 

just  as  the  modern  aeroplane  has  been  most  promi- 
nently associated  with  the  names  of  two  brothers, 
so  to  two  brothers,  Stephen  and  Joseph  Mont- 
golfier,  is  generally  ascribed  the  invention  of  the 
balloon.  Tradition  has  it  that,  inspired  originally 
by  reading  Dr.  Priestly 's  "  Experiments  Relating 
to  Different  Kinds  of  Air",  the  Montgolfiers,  who 
were  sons  of  Peter  Montgolfier,  a  paper  manufac- 
turer of  Annonay,  France,  were  next  impressed 
from  observation  of  the  clouds  with  the  idea  that 
if  they  could  fill  a  light  bag  with  "some  substance 
of  a  cloud-like  nature"  it  would  similarly  float  in 
the  atmosphere.  Accordingly — with  the  notion  of 
using  smoke  as  the  required  "substance" — 
Stephen,  who  appears  to  have  been  the  prime 
mover  in  the  enterprise,  started  to  experiment  with 
large  paper  bags,  of  capacities  up  to  700  cubic  feet, 
under  which  were  burned  fires  of  chopped  straw. 
Though  success  immediately  resulted,  it  is  inter- 
esting to  note  that  it  was  some  time  before  the 
brothers  realized  that  the  real  source  of  the  lift- 
ing effect  was  the  heating  of  the  air  within  the  bags 
and  not  the  smoke  with  which  they  sought  to  fill 
them. 

Having  demonstrated  the  possibility  of  making 
small  balloons  ascend,  the  Montgolfiers  next  built 
a  spherical  paper  balloon  thirty  feet  in  diameter, 
with  a  capacity  of  about  13,000  cubic  feet  and  pos- 
sessed of  a  consequent  ascensional  force,  when 
inflated  with  heated  air,  of  probably  500  pounds. 
This  balloon  was  sent  up  from  Annonay,  without 
passengers,  on  June  5,  1783,  in  the  presence  of 


LIGHTER-THAN-AIR  MACHINES  69 

many  spectators.  It  rose  to  an  estimated  height 
of  a  mile  and  a  half  before  the  air  within  it  cooled 
sufficiently  to  cause  its  descent,  ten  minutes  after 
its  release.  A  modern  reproduction  of  one  of  the 
first  Montgolfier  balloons  is  shown  in  Figure  2. 

Following  this  first  balloon  ascent,  on  August 
27,  1783,  M.  Faujas  de  Saint-Fond,  a  naturalist; 
M.  Charles,  a  professor  of  natural  philosophy  in 
Paris,  and  two  brothers  by  the  name  of  Robert, 
sent  up  a  hydrogen  balloon  from  the  Champ  de 
Mars,  in  Paris.  This  balloon,  thirteen  feet  in  diam- 
eter and  weighing  less  than  twenty  pounds,  was 
made  of  thin  silk  coated  with  caoutchouc,  and 
required  four  days  for  its  inflation,  the  hydrogen 
being  generated  by  the  action  of  500  pounds  of 
sulphuric  acid  on  half  a  ton  of  iron  filings — a  proc- 
ess that  only  very  recently  shows  signs  of  being 
superseded  (see  Page  99).  When  liberated  the 
balloon  rose  rapidly  to  a  height  of  about  3,000  feet, 
burst,  and  then  landed  three-quarters  of  an  hour 
later  in  a  field  near  Gonesse,  fifteen  miles  away, 
where  it  was  destroyed  by  terrified  peasants. 

The  next  balloon  ascent  was  that  of  a  spherical 
bag,  of  linen  covered  with  paper,  made  by  the 
brothers  Montgolfier.  This  balloon,  which  was  the 
second  of  the  same  material — the  first  having  been 
destroyed  by  a  storm  of  wind  and  rain  before  it 
could  be  used — had  a  capacity  of  52,000  cubic  feet, 
and  was  sent  up  from  Versailles,  France,  on  Sep- 
tember 19,  1783.  A  small  car  was  attached,  in 
which  were  placed  a  sheep,  a  cock,  and  a  duck, 
which  thus  had  thrust  upon  them  the  distinction 


70  VEHICLES  OF  THE  AIR 

of  being  the  first  balloonists.  The  descent  occurred 
eight  minutes  after  the  start,  and  the  sheep  and 
duck  were  uninjured.  The  cock  had  not  fared  so 
well,  and  his  condition  was  gravely  attributed  by 
the  savants  present  to  the  effects  of  the  tenuous 
atmosphere  of  the  upper  regions.  Calmer  subse- 
quent diagnosis,  however,  indicated  that  he  had 
been  trampled  upon  by  the  sheep. 

The  first  ascent  of  a  man-carrying  balloon  was 
one  ventured  by  Pilatre  de  Rozier,  who  entrusted 
himself  to  a  captive  balloon,  built  by  the  Mont- 
golfiers,  on  October  15, 1783.  The  balloon  was  per- 
mitted to  ascend  only  to  a  height  of  less  than  100 
feet,  at  which  elevation  it  was  kept  for  a  period  of 
a  little  over  four  minutes  by  continuous  heating 
of  the  air  inside  of  it  by  means  of  a  fire  of  chopped 
straw.  Following  this,  on  November  21,  1783,  de 
Rozier  and  a  friend,  the  Marquis  d'Arlandes,  made 
the  first  free  balloon  ascension,  in  which  the  start 
was  from  Paris,  with  the  descent  safely  accom- 
plished in  a  field  five  miles  from  the  French 
metropolis  after  about  twenty  minutes  of  drifting 
at  not  over  500  feet  high. 

It  is  recorded  that  Benjamin  Franklin,  who  was 
a  witness  of  this  first  aerial  voyage,  was  asked  by 
a  pessimistic  spectator  for  his  opinion  of  the  utility 
of  the  new  device,  to  which  Franklin  is  said  to  have 
replied,  "Of  what  use  is  a  new-born  babe?" 

Only  seven  days  after  the  foregoing,  on  Novem- 
ber 28,  there  was  made  from  Philadelphia,  under 
the  auspices  of  the  Philosophical  Academy  of  that 


LIGHTER-THAN-AIR  MACHINES  71 

city,  a  balloon  ascent  that  has  escaped  the  atten- 
tion of  most  of  the  writers  on  the  subject.  The 
enterprise  was  in  charge  of  two  local  scientists, 
Hopkins  and  Eittenhouse,  who  first  made  experi- 
ments by  sending  up  animals  in  a  car  attached 
to  forty-seven  small  hydrogen  balloons.  They  then 
persuaded  one  James  Wilcox,  a  carpenter,  to  go 
aloft,  with  the  result  that  to  this  man  belongs  the 
honor  of  having  first  ascended  with  a  hydrogen 
balloon.  The  descent,  which  barely  missed  being 
into  the  Schuylkill  River,  was  so  abrupt  that  the 
lone  passenger  dislocated  his  wrist. 

The  first  European  ascent  with  a  hydrogen  bal- 
loon was  made  on  December  1,  1783,  by  Charles 
and  Robert,  who  safely  accomplished  a  twenty- 
seven  mile  trip  at  about  fifteen  miles  an  hour  from 
Paris  to  Nesle,  France,  in  two  hours,  reaching  a 
height  of  2,000  feet.  At  Nesle  a  landing  was 
effected  and  Robert  got  out,  whereupon  Charles 
made  a  further  journey  of  two  miles  in  the  course 
of  which  it  is  asserted  he  rose  to  a  height  of  10,000 
feet,  at  which  altitude  he  suffered  severely  from 
cold  and  the  rapid  lowering  of  the  atmospheric 
pressure.  The  balloon  used  on  this  occasion  was 
over  twenty-seven  feet  in  diameter,  sewed  up  of 
varnished  silk  gores,  and  on  the  whole  very  well 
designed,  being  provided  with  a  net  and  valve. 
The  car  was  boat-like,  eight  feet  long,  and  weighed 
130  pounds.  Ballast  was  used  to  control  and  a 
barometer  to  measure  the  height.  Indeed,  nearly 
every  essential  feature  was  closely  similar  to  the 


72  VEHICLES  OF  TEE  AIR 

corresponding  features  in  the  best  modern  gas 
balloons,  which  therefore  date  back  more  defin- 
itely to  the  ingenious  Charles  than  to  any  other 
investigator. 

During  1784  balloons  became  common  through- 
out all  Europe  and  many  successful  ascents  were 
made.  The  first  woman  to  ascend  in  a  balloon  was 
a  Madame  Thible,  who  went  up  from  Lyons, 
France,  during  this  year. 

On  January  7,  1785,  a  remarkable  balloon  voy- 
age was  made  with  a  hydrogen  balloon  by  Jean- 
Pierre  Blanchard  and  an  American  physician 
named  Jeffries,  these  two  embarking  from  the  cliff 
near  Dover  castle  and  crossing  the  English  Channel 
to  the  forest  of  Guines,  in  France,  the  distance 
being  made  with  a  favorable  wind  in  something 
less  than  three  hours.  In  an  attempt  to  repeat  this 
feat,  on  June  15,  1785,  at  the  age  of  twenty-eight 
years,  Pilatre  de  Rozier,  the  first  aeronaut,  became 
also  the  first  victim  of  aerial  travel,  he  and  a  friend, 
M.  Romaine,  both  losing  their  lives  through  the 
balloon,  which  was  of  the  Montgolfier  type,  catch- 
ing fire  at  a  considerable  height. 

Since  the  foregoing,  which  are  the  more  impor- 
tant and  interesting  of  the  early  balloon  ascensions, 
thousands  of  others  have  been  made  all  over  the 
world.  In  the  course  of  these  some  utility  has 
developed  in  the  way  of  military  and  meteorolog- 
ical observation,  but  in  most  cases  the  immediate 
purposes  and  the  ultimate  results  have  not  been 
more  serious  than  the  catering  to  an  uncertain 
scientific  interest  and  an  unfailing  willingness  of 


LIGHTER-THAN-A1R  MACHINES          73 

the  crowd  to  pay  its  money  for  the  spectacle  of  a 
parachute  jump.  However,  despite  the  extreme 
and  often  unnecessary  risks  that  have  been  taken 
by  the  ignorant  or  reckless,  an  examination  of  the 
statistics  of  ballooning  discloses  a  surprisingly 
small  number  of  fatalities  in  proportion  to  the 
number  of  ascensions  that  have  been  made. 

The  history  of  ballooning  has  been  from  the  first 
closely  associated  with  warfare.  Indeed,  it  is  said 
that  one  of  the  avowed  purposes  of  the  Montgol- 
fiers  was  to  render  more  effective  the  siege  of 
Gibraltar,  by  the  combined  French  and  Spanish 
forces,  who,  however,  gave  up  the  fight  some  time 
before  the  Montgolfiers  proved  the  practicability 
of  the  balloon.  Subsequently  a  regular  "  aero- 
static corps"  was  attached  to  the  French  army, 
and  did  service  during  the  French  Eevolution  and 
Napoleon's  Egyptian  campaign.  Considerable 
utility  was  demonstrated  during  the  battle  of  Fleu- 
rus,  in  the  course  of  which  two  aerial  reconnais- 
sances from  a  captive  balloon  contributed  mate- 
rially to  the  victory  of  the  French  over  the  Aus- 
trians.  But  when  a  balloon  sent  up  in  honor  of 
his  coronation  was  wrecked  against  a  statue  of 
Nero,  the  great  Corsican  seems  to  have  lost  inter- 
est in  the  new  invention. 

Some  use  of  balloons  was  made  by  both  sides  in 
the  American  Civil  War,  and  in  the  Spanish- Amer- 
ican war  a  balloon  was  successfully  employed  to 
discover  the  presence  of  Cervera's  fleet  in  Santiago 
harbor,  but  by  far  the  most  important  use  ever 


74  VEHICLES  OF  THE  AIR 

made  of  balloons  was  in  the  siege  of  Paris,  dur- 
ing the  Franco-Prussian  war  in  1870.  In  this 
remarkable  application  seventy-three  postal  bal- 
loons were  built  and  sent  out  from  the  beleaguered 
city  with  cargoes  of  mail,  and  carrier  pigeons  which 
were  used  to  bring  back  replies  to  the  messages. 
In  this  way  over  3,000,000  letters  were  transmitted, 
those  brought  back  by  the  pigeons  being  reduced 
so  small  by  photography  that  5,000  separate 
missives  weighed  only  nine  grains. 

One  of  the  longest  .balloon  voyages  on  record — 
not  exceeded  until  within  comparatively  recent 
years — was  that  of  John  Wise  from  St.  Louis  to 
Henderson,  N.  Y.,  in  July  1859.  This  journey  was 
accomplished  in  a  lively  gale,  with  the  result  that 
the  distance  of  950  miles  was  covered  in  nineteen 
hours.  October  9-11,  1900,  Count  Henry  de  la 
Vaulx  and  Count  Castillion  de  Saint  Victor  super- 
seded the  Wise  record  by  a  journey  from  Vin- 
cennes,  France,  to  Korostichev,  Russia,  a  distance 
of  1,139  miles,  in  thirty-five  hours  and  forty-five 
minutes. 

The  present  balloon  duration  record  is  held  by 
Lieutenant-Colonel  Schaeck,  of  the  Swiss  Aero 
Club,  who  in  the  balloon  Helvetia,  sent  up  from 
Berlin  on  October  11, 1909,  remained  in  the  air  sev- 
enty-two hours,  finally  landing  in  the  sea  off  the 
coast  of  Norway. 

The  balloon  altitude  record  was  long  credited  to 
Glaisher  and  Coxwell,  who  on  September  3,  1862, 
reached  a  height  claimed  to  have  been  36,090  feet. 
Some  discredit  has  been  cast  upon  the  achievement 


LIGHTER-THAN-AIR  MACHINES  75 

by  doubt  concerning  the  possibility  of  sustaining 
life  at  such  a  height  without  carrying  a  supply  of 
artificial  oxygen,  with  the  result  that  the  maxi- 
mum altitude  is  now  believed  to  have  been  not 
over  29,520  feet.  On  December  4, 1894,  Professors 
Berson  and  Gross  ascended  from  Berlin  and  defi- 
nitely recorded  an  altitude  of  28,750  feet.  Subse- 
quently, on  July  31,  1901,  Berson  and  Sirring,  of 
the  "Berlin  Verein  fur  Luftschiffahrt",  reached  a 
height  of  35,400  feet,  using  oxygen  tanks. 

So-called  "  sounding  balloons ",  for  meteorolog- 
ical investigation,  but  without  passengers  and  car- 
rying only  self-registering  instruments,  have 
reached  much  greater  heights,  the  record  being 
held  by  the  balloon  which  was  sent  up  from  the 
Uccle  Observatory  in  Belgium  (see  Page  44). 

SPHERICAL  TYPES 

The  simplest  and  in  some  respects  the  most 
advantageous  form  of  balloon  is  the  spherical, 
because  a  given  surface  of  envelope  will  enclose  a 
greater  volume  in  the  form  of  a  sphere  than  in 
any  other  shape.  Furthermore,  since  a  sphere 
is  the  form  into  which  any  flexible  hollow  struc- 
ture tends  to  distort  under  the  influence  of  an 
interior  pressure,  a  sphere  is,  therefore,  the  only 
form  not  subject  to  distortion  stresses. 

In  the  construction  of  spherical  balloons,  the 
plan  usually  followed  is  to  cut  the  material  into 
narrow,  double-tapered  gores,  laid  out  as  shown 
in  Figure  3.  These  gores  when  sewn  together 
along  their  adjacent  edges  afford  a  practically 


76 


VEHICLES  OF  THE  AIR 


perfect  approximation  to  the  required  form,  as  is 
indicated  at  a,  b,  c,  and  d,  Figure  3.    The  correct 

shape  of  the  gores  is  found 
by  laying  them  out  as 
shown  in  Figure  3. 

Practically  all  non-diri- 
gible balloons  are  now  made 
spherical — sometimes  modi- 
fied into  a  pear-shape  to 
provide  the  open  neck  com- 
monly used  to  allow  for  ex- 
pansion and  contraction  of 
the  gas.  Except  from  the 
standpoint  of  dirigibility 
there  are  few  advantages 
and  many  positive  disad- 
vantages in  all  but  the 
spherical  form.  One  of  the 
most  serious  of  these  dis- 
advantages is  the  necessity 
for  some  sort  of  rigid  or 
semi-rigid  construction  to 
protect  non-spherical  struc- 


FIGURE  3. — Layout  of 
Gores  for  Spherical  Balloon. 
The  dimension  a  e  is  one-half 
of  the  circumference  of  the 
balloon  and  the  dimension 
b  c  is  the  circumference  di- 
vided by  the  number  of  gores 
it  is  intended  to  use.  These 
major  dimensions  settled 
upon,  intermediate  points  on 
the  gore  curve,  as  at  q,  will 
be  found  as  shown  at  the 
junctures  of  lines  projected 
from  similar  points  on  the 
diameters  of  the  large  and 
small  semicircles. 


tures  against  dangerous  distortion. 

DIRIGIBLE  BALLOONS 

Naturally  in  the  development  of  the  balloon 
it  was  early  attempted  to  navigate  definite 
courses  from  one  point  to  another,  either  in  calm 
weather  or  independent  of  the  direction  of  the 
winds.  It  was  soon  seen  to  be  manifestly  impos- 


LIGHTER-THAN-AIR  MACHINES  77 

sible,  though,  to  derive  propulsion  from  the  wind 
except  directly  before  the  wind,  anything  analo- 
gous to  the  tacking  of  a  ship  being  out  of  the  ques- 
tion because  of  the  lack  of  any  fulcrum  such  as  is 
provided  by  the  hull  of  a  ship  in  the  water.  This 
compelled  recourse  to  various  systems  of  internal 
power  development  and  application,  commencing 
with  the  hand-manipulated  oars  and  sails  of  early 
investigators  and  coming  down  to  the  engines  and 
propellers  of  modern  dirigibles. 

Another  obvious  line  of  improvement  along 
which  much  work  has  been  done  consists  in  the 
reduction  of  the  head  resistances  against  which  it 
is  necessary  to  propel  a  balloon,  reduction  of  these 
resistances  being  the  ideal  held  in  view  in  the  con- 
struction of  the  many  cylindrical,  cigar-shaped, 
and  other  elongated  and  pointed  gas  bags  with 
which  the  modern  student  of  this  subject  is 
familiar. 

So  far,  however,  all  successes  achieved  with 
dirigible  balloons  have  been  more  spectacular  than 
practical,  and  there  is  little  reason  for  expecting 
that  results  of  more  serious  value  are  in  any  pres- 
ent prospect  of  attainment.  Certainly,  admitting 
the  possibility  of  an  exceedingly  limited  and  pre- 
carious utility  for  the  dirigible  in  warfare,  it  is,  in 
the  opinion  of  those  best  qualified  to  judge,  most 
unlikely  ever  to  assume  the  least  importance  as  a 
means  of  travel. 

The  great  difficulties  with  the  balloon  are  its 
inescapably  enormous  volume  and  its  strict  limita- 


78  VEHICLES  OF  THE  AIR 

tions  in  weight  of  structure.  To  ascend,  a  balloon 
must  be  lighter  than  the  volume  of  air  it  displaces 
and,  the  weight  of  a  given  volume  of  air  being  fixed 
and  unchangeable,  no  possible  discovery  or  inven- 
tion (unless  of  some  structural  materials  of  alto- 
gether ultra-terrestrial  strength)  can  open  a  way 
of  escape  from  this  inexorable  factor  of  the  prob- 
lem. A  sphere  of  air  ten  feet  in  diameter  weighs 
almost  exactly  seventy-six  pounds,  while  a  simi- 
lar sphere  of  hydrogen  weighs  something  less 
than  six  pounds.  Consequently,  enclosing  the 
hydrogen  in  an  envelope  and  causing  it  to  occupy 
the  space  of  an  equivalent  volume  of  air  manifestly 
affords  a  gross  lifting  capacity  within  this  consid- 
erable bulk  of  seventy-six  minus  six — only  seventy 
pounds.  Evidently  the  unlikely  discovery  of  some 
gas  lighter  than  hydrogen  can  effect  no  material 
benefit,  for  even  should  it  become  feasible  to  encase 
a  vacuum  of  the  requisite  size,  as  some  enthusiasts 
have  hoped,  this  could  help  the  sustention  only  to 
the  extent  of  the  eliminated  six  pounds  of  hydro- 
gen. And  always  within  whatever  lifting  capacity 
there  may  be  provided  must  come  not  only  the 
loads  that  it  is  required  to  convey,  but  also  the 
weight  of  the  structure  and  the  enveloping  mate- 
rial, which  it  is  highly  desirable  to  have  far 
stronger  and  rigider  than  the  strongest  and  rigid- 
est  ever  likely  to  be  attainable. 

Prom  all  of  which  it  follows  that  the  best  of 
balloons  are,  and  are  likely  to  continue,  hopelessly 
bulky  and  fearfully  flimsy,  and  of  only  the  very 


LIGHTER-THAN-AIR  MACHINES          79 

smallest  lifting  capacities  in  proportion  to  their 
size.  Held  captive  or  let  drift  with  the  wind,  they 
can  be  made  to  afford  fair  security  with  very  lim- 
ited utility.  Provided  with  motors  and  propelling 
means,  they  not  only  oppose  the  resistance  of  enor- 
mous areas  to  rapid  motion,  but  also  prove  of  such 
fragility  that  their  structure  must  inevitably  col- 
lapse under  the  heavy  stresses,  should  sufficient 
power  within  the  weight  limit  ever  become  avail- 
able to  drive  them  greatly  faster  than  the  maxi- 
mums  of  twenty-five  or  thirty  miles  an  hour  that 
have  been  so  far  attained,  and  which  are  nowhere 
near  sufficient  to  combat  ordinary  adverse  winds. 

The  cost  of  gas  alone  for  each  filling  of  a  large 
balloon  at  present  places  it  utterly  out  of  the  ques- 
tion for  performing  commercial  service  at  reason- 
able cost.  About  a  thousand  dollars  worth  of  gas 
on  the  basis  of  the  most  economical  production  pos- 
sible (see  Page  99)  is  required  for  each  inflation  of 
a  Zeppelin  balloon,  443  feet  long  and  42  feet  in 
diameter,  but  possessed  of  a  reserve  carrying  capa- 
city of  only  five  and  a  half  tons.  Moreover,  no  bal- 
loon builder  as  yet  has  been  able  within  the  weight 
limitation  to  devise  an  envelope  capable  of  retain- 
ing a  filling  of  gas  for  more  than  a  limited  period 
(see  Page  74) — not  to  consider  the  further  loss  that 
occurs  in  the  necessary  trimming  of  the  craft  to  de- 
sired heights  by  alternate  discharges  of  gas  and 
ballast — the  latter  of  which,  by  the  way,  is  a  burden 
to  be  reckoned  with  in  all  estimates  of  passenger 
and  cargo-carrying  capacities. 


80 


VEHICLES  OF  THE  AIR 

HISTORY 


One  of  the  earliest  well  studied  attempts  to  pro- 
duce a  successful  dirigible  balloon  was  made  by 
Henri  Giffard,  in  France,  in  1852.  In  Giffard 's 


FIGURE  4. — Giffard's  Dirigible  Balloon.  Propelled  by  3-horsepower 
steam  engine,  weighing,  with  fuel  and  water  for  one  hour,  462  pounds. 
Length  144  feet,  diameter  39  feet,  capacity  88,300  cubic  feet.  Made  7  miley 
an  hour  in  1852. 


machine,  illustrated  in  Figure  4,  the  gas  bag 
was  spindle-shaped,  144  feet  long.  Though  the 
motor  proved  very  weak  it  was  found  possible  in 
very  quiet  air  to  steer  and  to  travel  in  circles,  with 
a  maximum  speed  of  scarcely  seven  miles  an  hour. 
In  1870  another  French  experimenter,  Dupuy 
de  Lome,  at  Vincennes,  tried  out  a  machine  pro- 
vided with  an  enormous  two-bladed  propeller,  29 
feet  6  inches  in  diameter.  This  propeller  was 
turned  slowly  by  the  muscular  efforts  of  the  eight 
passengers  and,  in  a  breeze  of  about  twenty-six 
miles  an  hour,  "a  deviation  of  twelve  degrees" 


LIGHTER-THAN-AIR  MACHINES 


81 


from    a    normal    straight    drifting    course    waa 
obtained. 

At  Grenelle,  France,  in  1884,  Gaston  and  Albert 
Tissandier  maneuvered  for  two  and  a  half  hours  in 
the  dirigible  illustrated  in  Figure  5.  This  was 
driven  by  a  one  and  one-third  horsepower  Siemens 
electric  motor,  weighing  121  pounds  and  taking 
current  from  a  bichromate  battery  weighing  496 


FIGURE  5. — Tissandier's  Dirigible  Balloon.  Propelled  by  1% -horsepower 
electric  motor  and  primary  battery,  weighing  616  pounds.  Length  92  feet, 
diameter  30  feet,  capacity  37,440  cubic  feet.  Made  7  miles  an  hour  in  1884. 


pounds.  The  propeller  was  two-bladed,  nine  feet  in 
diameter.  In  a  wind  of  eight  miles  an  hour  and 
with  a  horsepower  output  estimated  to  have  run  as 
high  as  one  and  a  half,  a  large  semicircle  was  suc- 
cessfully described,  following  which,  in  a  wind  of 
seven  miles  an  hour,  headway  was  made  across  the 
wind  and  various  evolutions  performed  above  the 
Grenelle  observatory. 


82 


VEHICLES  OF  THE  AIR 


Following  the  Tissandier  experiments,  Com- 
mandant Eenard  of  the  balloon  corps  of  the  French 
army,  on  September  23,  1885,  navigated  from 
Chalais-Meudon  to  Paris  against  a  light  wind  and 
returned  with  little  difficulty  to  the  point  of  depar- 


FIOURB  6. — Renard  and  Kreb's  Dirigible  Balloon.  Propelled  by  9-horse- 
power  electric  power  plant,  weighing  1,174  pounds.  Length  165  feet,  diam- 
eter 27  feet,  capacity  65,836  cubic  feet.  Made  14  miles  an  hour  in  1885. 

ture,  making  several  ascents  and  descents  en  route. 

Little  more  of  especial  interest  was  accom- 
plished until  in  1901  a  young  Brazilian,  Alberto 
Santos-Dumont,  commenced  in  France  a  record- 
breaking  series  of  performances  with  a  succession 
of  dirigibles.  His  most  notable  accomplishment 
was  winning,  on  the  fourth  attempt,  with  his  San- 
tos-Dumont No.  6,  the  M.  Deutsch  prize  of  about 
$15,000  on  October  9,  1901,  for  traveling  from  the 
Pare  d 'Aerostation  at  St.  Cloud  to  and  around  the 
Eiffel  tower  and  back.  His  time  was  about  thirty 
minutes  for  the  distance  of  nine  miles.  The  bal- 
loon, which  was  the  sixth  dirigible  built  by  Santos- 
Dumont,  was  108  feet  long  and  20  feet  in  diameter, 
and  was  propelled  by  a  16-horsepower  gasoline 
automobile  engine.  Subsequent  to  this  Santos 
Dumont  built  at  least  six  more  dirigibles. 

The  Lebaudy  brothers,  in  1903,  built  a  dirigible 


LIGHTER-THAN-AIR  MACHINES  83 

185  feet  long  and  32  feet  in  diameter  which,  with 
a  40-horsepower  gasoline  motor,  is  said  to  have 
attained  a  speed  of  24  miles  an  hour. 

In  England  the  most  successful  early  dirigibles 
were  those  of  Spencer,  Beedle,  and  Dr.  Barton. 
The  first  of  these  was  93  feet  long  and  24  feet  in 
diameter,  with  a  24-horsepower  motor.  The  Beedle 
balloon  was  of  the  same  proportions,  but  had  only 
a  12-horsepower  motor.  Dr.  Barton's  balloon  was 
170  feet  long  and  40  feet  in  diameter  and  was  pro- 
pelled by  two  separate  50-horsepower  gasoline 
motors.  It  was  complicated  by  an  excess  of  aero- 
plane stabilizing  surfaces  that  undoubtedly  sub- 
tracted from,  rather  than  added  to,  its  utility. 

Recent  military  dirigible  balloons  of  some  suc- 
cess or  prominence  are  the  English  "Baby",  the 
French  "Liberte"  and  "Republique",  and  the 
"  Ville  de  Nancy",  and  the  German  Gross  and  Par- 
seval  balloons.  The  first  of  these  is  very  small  and 
makes  a  speed  of  only  7  miles  an  hour,  but  it  is 
exceedingly  convenient  and  portable.  The  "Lib- 
erte" and  the  "Republique"  are  up-to-date  devel- 
opments of  the  Lebaudy  type,  and  the  "Ville  de 
Nancy",  illustrated  in  Figure  18,  is  a  Clement- 
Bayard  product  designed  for  the  Russian  army. 
The  latter  airship,  which  is  180  feet  long  and  33 
feet  in  diameter,  with  a  capacity  of  180,000  cubic 
feet,  is  provided  with  an  internal  balloon  or  bal- 
lonet,  of  the  type  illustrated  in  Figure  13,  by  which 
the  main  gas  bag  is  kept  constantly  distended  under 
an  internal  pressure  of  a  little  over  seven  pounds 
to  a  square  foot.  This  balloon  made  its  first  ascent 


84  VEHICLES  OF  THE  AIR 

on  June  27, 1909,  and  subsequently,  on  June  28  and 
July  2,  it  twice  remained  five  hours  in  the  air. 
Late  in  August,  1909,  it  was  badly  damaged  by  an 
inadvertent  descent  into  the  Seine,  occasioned  by 
a  heavy  wind  coming  up  while  it  was  at  a  height 
of  4,000  feet.  On  September  25,  1909,  the  "Ke- 
publique"  exploded  at  a  height  of  500  feet,  near 
Paris,  and  fell  to  the  ground,  causing  the  death 
of  four  French  army  officers. 

The  latest  Gross  dirigible  has  a  capacity  of 
270,000  cubic  feet  and  is  propelled  by  two  motors 
with  a  total  output  of  75  horsepower,  driving  two 
propellers.  Twin  ballonets  are  used  to  keep  the 
envelope  taut,  and  journeys  of  over  fifteen  hours' 
duration  have  been  accomplished. 

On  May  22,  1909,  a  race  was  held  near  Berlin 
between  the  "  Gross  II"  and  the  "Parseval  II", 
which  is  of  similar  construction.  The  contest  was 
a  tie,  with  a  time  of  fifteen  minutes  for  a  circuit 
over  the  Templehof  parade  grounds. 

A  very  curious  small  dirigible,  designed  by  Isa- 
buro  Yamada,  was  used  by  the  Japanese  army 
during  the  siege  of  Port  Arthur.  This  balloon, 
which  was  110  feet  long,  differed  from  all  other 
dirigibles  in  that  the  50-horsepower  gasoline  motor 
was  in  a  separate  car,  much  below  and  in  advance 
of  the  car  proper,  to  reduce  the  danger  of  fire. 

A  dirigible  that  has  been  much  in  the  public 
eye  is  the  " America",  designed  by  Melvin  Vani- 
man  and  Louis  Godard  for  use  in  the  polar  explora- 
tion project  promoted  by  "Walter  Wellman.  This 


LIGHTER-THAN-AIR  MACHINES  85 

balloon,  details  of  which  are  illustrated  in  Figures 
12,  19,  and  20,  is  184  feet  long  and  52  feet  in 
diameter,  with  a  capacity  of  258,500  cubic  feet  of 
gas.  The  total  ascensional  force  at  sea  level  is 
19,000  pounds,  the  weight  of  the  envelope  3,600 
pounds,  and  that  of  the  car,  motors,  and  full  tanks 
of  fuel  4,500  pounds.  Propulsion  is  by  two  bevel- 
gear-driven  steel  propellers,  11  feet  in  diameter, 
revolved  by  a  70-80-horsepower  Lorraine-Dietrich 
motor.  An  80-horsepower  Antoinette  motor  with 
a  duplicate  pair  of  propellers  is  kept  in  reserve. 
Despite  the  expenditure  of  large  sums  of  money 
and  attempts  made  season  after  season,  the  nearest 
this  balloon  has  come  to  reaching  the  pole  has  been 
a  thirty-mile  flight  from  its  base  in  Spitzbergen. 

In  the  United  States  little  has  been  done  toward 
the  development  of  dirigible  balloons,  such  activity 
as  there  has  been  being  confined  to  the  more  or 
less  perfect  copying  of  the  best  foreign  construc- 
tions. Knabenshue,  Baldwin,  and  Stevens  have 
been  the  most  successful  among  the  American 
dirigible  balloon  navigators. 

In  every  way  the  most  interesting  and  most 
important  devices  in  this  field  of  aerial  navigation 
are  the  great  dirigibles  of  Count  Zeppelin,  which 
unquestionably  are  so  far  in  advance  of  other  con- 
structions of  the  same  general  character  that  their 
points  of  merit  constitute  a  fair  measure  of  all 
dirigible  practicability,  while  their  more  serious 
shortcomings  are  reasonably  to  be  regarded  as 
among  the  defects  of  all  possible  craft  of  the 
lighter-than-air  type. 


86  VEHICLES  OF  THE  AIR 

In  his  work  Zeppelin  appears  particularly  to 
have  sought  the  attainment  of  the  utmost  possible 
length  in  proportion  to  diameter,  with  a  view  to 
keeping  down  head  resistance  while  at  the  same 
time  securing  lifting  capacity.  This  in  turn  has 
compelled  recourse  to  a  rigid  structure  for  the  gas 
bag  as  the  only  possible  means  of  keeping  one  of 
such  length  in  shape. 

Safety  has  been  provided  by  a  multiplication 
of  lifting  units,  there  being  seventeen  separate 
and  independent  balloons  enclosed  between  par- 
titions in  the  structure.  Great  lifting  capacity  is 
secured  by  sheer  size,  while  height  control  is  in 
large  measure  attained  by  the  provision  of  fin  and 
rudder-like  stabilizing  or  balancing  surfaces. 

The  partially-sectioned  illustration  in  Figure 
17  affords  an  excellent  idea  of  the  construction  of 
all  the  Zeppelins,  of  which  several  have  been  built. 
The  first  of  these  were  commenced  in  the  late 
nineties  at  Friedrichshafen,  on  Lake  Constance, 
where  there  was  built  a  mammoth  floating  balloon 
house,  500  feet  long,  80  feet  wide,  and  70  feet  high, 
mounted  on  ninety-five  pontoons.  This  house, 
being  anchored  only  at  its  forward  end,  was  free 
to  swing  so  as  always  to  face  the  wind,  with  the 
result  that  the  balloon  could  be  taken  out  and 
housed  without  danger  of  collision. 

The  first  Zeppelin  balloon  was  410  feet  long 
and  39  feet  in  diameter,  with  its  framing  made  up 
of  sixteen  twenty-four-sided  polygonal  rings,  sepa- 
rated by  spaces  of  26  feet.  The  rings,  stays  and 
even  the  wire  bracing  were  at  first  made  of  "wol- 


LIGHTER  THAN  AIR  MACHINES          87 

framinium"  (see  Page  385),  but  in  subsequent 
models  it  is  said  that  this  metal  has  been  by  degrees 
given  up,  until  in  balloons  now  building  for  the 
German  government  it  is  almost  entirely  replaced 
with  wood  and  steel. 

Over  the  framing  and  between  the  chambers 
ramie  netting  was  liberally  applied,  reinforcing 
both  structure  and  fabric.  The  nose  of  the  bal- 
loon was  capped  with  a  sheet-aluminum  bow  plate. 

The  compartments,  which  in  the  first  model 
contained  a  total  of  351,150  cubic  feet  of  hydrogen, 
affording  a  total  lift  of  eleven  tons,  are  lined  with 
rather  lighter  balloon  fabric  than  is  necessary  for 
non-rigid  dirigibles,  and  this  fabric  is  proofed  with 
the  gray  quality  of  rubber  which  affords  the  high- 
est resistance  to  the  leakage  of  gas.  Over  the 
outside  of  the  framing  a  non-gasproof  fabric  is 
used.  A  space  of  about  two  feet  is  provided  all 
around  the  internal  balloons,  under  this  external 
cover,  to  serve  as  a  protection  from  the  heat  of 
the  sun. 

Two  boat-like  cars,  at  the  ends  of  a  stiffen- 
ing keel  of  latticed  framework,  are  provided  on 
the  underside  of  the  cylindrical  body,  and  are  suffi- 
cient to  float  the  whole  craft  on  the  water.  These 
cars,  each  21.32  by  5.96  by  3.28  feet,  are  connected 
by  a  passageway  326  feet  long  and  from  one  to  the 
other  a  cable  is  stretched,  along  which  a  sliding 
weight  can  be  adjusted  to  trim  the  craft  fore  and 
aft.  In  the  first  Zeppelin  a  15-horsepower  Daim- 
ler motor — at  700  revolutions  a  minute — was 


88  VEHICLES  OF  THE  AIR 

located  in  each  car,  each  motor  driving  two  four- 
bladed  propellers,  3  |feet  in  diameter. 

The  speed  of  the  first  Zeppelin  was  not  over 
seventeen  miles  an  hour  and  only  short  journeys 
were  attempted,  but  in  later  models  in  which  the 
sizes  have  been  increased  materially  and  as  much 
as  350  horsepower  applied  through  six  three  or 
two-bladed  propellers,  speeds  of  as  high  as  twen- 
ty-five or  perhaps  thirty  miles  an  hour  have  been 
maintained  in  calm  air  for  distances  as  great  as 
950  miles.  With  the  wind  the  speed  is,  of  course, 
higher,  but,  conversely,  it  is  correspondingly  lower 
when  the  wind  is  adverse. 

Landing  with  the  balloons  of  the  Zeppelin  type 
always  has  proved  precarious,  especially  when  the 
descent  has  not  been  on  water.  Of  the  several  that 
have  been  built,  one  has  been  burned  and  all  of  the 
others  more  or  less  seriously  damaged  at  different 
times  in  coming  to  the  ground. 

Nevertheless,  at  least  the  German  government 
continues  to  interest  itself  in  this  phase  of  aero- 
nautics, and  at  the  time  this  is  written  is  reported 
to  be  building  dirigibles  of  the  Zeppelin  type  even 
larger  than  any  that  heretofore  have  been 
constructed. 

The  map  in  Figure  270  shows  the  more  impor- 
tant of  the  Zeppelin  journeys. 

SPHERICAL  TYPES 

Very  few  balloons  of  the  true  dirigible  type 
have  been  built  with  spherical  envelopes,  the  most 
noteworthy  being  one  of  Blanchard's  first  bal- 


LIGHTER-THAN-AIR  MACHINES  89 

loons,  which  he  sought  to  propel  by  hand-manipu- 
lated wings  or  oars. 

However,  all  balloons  may  be  said  to  be  in  some 
degree  dirigible,  even  those  of  ordinary  spherical 
types  being  capable  of  a  slight  degree  of  control 
by  the  manipulation  of  drag  ropes,  as  is  explained 
on  Page  114. 

ELONGATED  TYPES 

As  has  been  previously  explained,  to  reduce 
head  resistances  and  permit  of  special  strengthen- 
ing of  the  bow  surfaces,  practically  all  dirigible 
balloons  are  given  elongated  forms,  necessitating 
structural  stiffening  beyond  what  is  obtainable 
by  mere  strength  and  guying  of  the  envelope  alone. 
There  are  two  principal  means  of  attaining  such 
stiffness  as  is  to  be  had — one  the  use  of  an  under- 
frame  or  long  truss-like  car  to  which  the  envelope 
is  securely  stayed  at  intervals,  and  the  other  the 
employment  of  internal  strengthening  within  the 
gas  bag  itself.  The  first  of  these  constructions, 
which  has  been  termed  "semi-rigid"  to  distin- 
guish it  from  the  second  type,  is  the  one  used  in 
practically  all  dirigible  balloons  except  the  Zep- 
pelin. The  latter  machine  is  not  only  the  foremost 
exponent,  but  is  also  practically  the  sole  represent- 
ative of  the  "rigid"  system,  its  details  being 
described  in  Pages  85  to  88,  and  in  Figure  17. 

Pointed  Ends  to  reduce  air  resistance  are  util- 
ized in  most  elongated  dirigible  constructions,  but 
probably  have  little  if  any  advantage  in  this 


90  VEHICLES  OF  THE  AIR 

regard  over  hemispherical  ends;  besides  which 
they  are  heavier  and  less  strong. 

Rounded  Ends,  of  exact  hemispherical  shape, 
are  geometrically  and  mechanically  the  lightest, 
simplest,  and  most  stable  forms  to  resist  the  end 
pressures  in  cylindrical  envelopes,  while,  as  is  sug- 
gested in  the  previous  paragraph,  there  is  no 
ground  for  supposing  that  they  noticeably  increase 
head  resistances — especially  at  such  speeds  as 
have  been  attained  so  far. 

Sectional  Construction,  though  not  altogether 
new,  has  been  worked  out  in  more  detail  and  is 
more  practically  applied  in  the  Zeppelin  than  in 
any  previous  airship.  In  the  great  balloons  of  this 
type — see  Page  96  and  Figure  17 — the  sixteen  or 
seventeen  disk-like  sections  are  entirely  indepen- 
dent of  one  another,  so  that  leakage  from  any  one 
can  not  affect  the  others. 

The  Effect  of  Size  on  balloon  design  is  a  subject 
concerning  which  there  is  much  misunderstanding. 
It  is  asserted,  for  example,  that  doubling  the 
dimensions  of  a  balloon  cubes  its  capacity  while 
only  squaring  the  areas  of  its  surfaces.  This  is, 
of  course,  perfectly  true,  but  the  consequent  rea- 
soning that  this  makes  it  possible  to  secure  greater 
proportionate  strength  with  each  increase  in  size 
seems  largely  unwarranted.  For,  to  maintain  a 
proportionate  strength,  it  is  necessary  to  double 
the  thickness  of  the  surfacing  material  with  the 
doubling  in  size,  with  the  result  that  the  quan- 
tity of  material  used  is  cubed,  after  all,  just  as 
the  capacity  is.  Even  at  this,  though,  the  strength 


2.  o  §    j 

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09  »o  2 

§ '«  ^^ 


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If  a! 


HI! 

i^s? 


LIGHTER-THAN-AIR  MACHINES  91 

possible  in  a  balloon  would  seem  to  advance  in 
proportion  to  increase  in  its  lifting  capacity, 
whereas  in  an  aeroplane  there  is  the  unavoidable 
rapid  gain  of  the  weights  over  the  areas.  Never- 
theless, it  remains  a  safe  general  rule  applicable 
to  all  structures,  that  the  smaller  the  size  the 
greater  the  proportionate  strength  with  a  given 
weight  of  material.  One  distinct  advantage  that 
comes  from  great  size  is  the  gain  of  the  lifting 
capacity  over  the  projected  area — the  one  cubing 
while  the  other  squares  with  each  increase  in  size. 
This  feature  definitely  permits  the  provision  and 
application  of  more  power  per  unit  of  forward 
resisting  surface  in  large  balloons  than  in  small. 

ENVELOPE  MATERIALS 

In  the  design  of  balloons,  much  effort  has  been 
put  forth  to  develop  the  lightest,  strongest,  and 
most  impervious  materials  that  can  be  had  for 
envelope  construction.  In  the  course  of  these 
experiments  every  art  and  every  country  has  been 
ransacked  to  find  new  fabrics,  varnishes,  etc.  The 
result  of  years  of  investigation  and  research,  how- 
ever, has  been  to  settle  the  superiority  of  silk,  cot- 
ton, and  linen  among  the  fabrics,  and  linseed  oil 
and  rubber  as  gas-proofing  materials.  In  the 
accompanying  illustrations  and  captions,  Figure  7, 
an  idea  is  given  of  the  appearance  and  character- 
istics of  some  typical  modern  balloon  fabrics,  made 
by  several  of  the  more  prominent  manufacturers 
of  these  materials. 

Naturally,  much  the  same  materials  that  are 


92  VEHICLES  OF  THE  AIR 

suitable  for  aeroplane  surfaces  are  suitable  for 
balloon  envelopes,  though  if  any  distinction  exists 
it  is  that  the  balloon  envelope  requires  to  be  most 
heavy  and  impervious,  while  aeroplane  surfaces 
may  be  very  light  and  need  not  be  absolutely  air- 
proof  (see  Figure  184). 

Large  balloons  generally  require  heavier  envel- 
opes than  small,  because  of  the  greater  area  and 
consequently  greater  stresses.  An  exception  to 
this  rule  is  the  case  of  rigid  balloons  of  the  Zep- 
pelin type,  in  which,  the  necessary  strength  being 
chiefly  afforded  by  the  framing,  much  lighter  cov- 
ering materials  can  be  used  than  in  the  balloons  of 
other  types  of  similar  size. 

Sheet  Metal  as  a  balloon  covering  probably  was 
first  exploited  in  Lana's  ingenious  plan  of  the  cop- 
per-covered vacuum  (see  Page  67).  Since  then  it 
has  not  progressed  notably  in  practical  application 
to  the  purpose  in  view,  though  it  is  perennially 
reinvented  on  paper  by  persons  whose  zeal  to 
achieve  is  greater  than  their  technical  equipment. 
Excellent  rubber-coated  balloon  fabrics  are  to  be 
had  weighing  no  more  than  six  ounces  to  the 
square  yard,  and  with  a  tensile  strength  of  100 
pounds  to  each  inch  of  width.  Sheet  aluminum  of 
the  same  weight  would  be  only  TTVa-  -inch  thick, 
would  have  a  tensile  strength  of  not  over  eighty 
pounds  to  each  inch  of  width,  and  would  crack 
and  leak  with  the  slightest  straining  or  denting — 
not  to  consider  the  impossibility  of  fastening  the 
sheets  to  the  framing  and  one  another  without 
creating  holes  and  bad  joints  beyond  toleration. 


LIGHTER-THAN-AIR  MACHINES          93 

Using  steel,  which  is  only  three  times  as  heavy 
as  aluminum  and  ten  times  as  strong,  the  plates 
would  be  Tinnr  -inch  thick  and  would  sustain  200 
pounds  to  each  inch  of  width,  but  the  difficul- 
ties of  construction,  maintenance,  and  adequate 
protection  from  rust  would  be  all  but  insuperable. 

Silk  possesses  the  superiority  over  cotton  that 
it  does  not  rot  as  readily,  while  it  is  materially 
stronger  under  direct  tensile  stresses,  though  it  is 
not  nearly  as  capable  of  withstanding  repeated 
flexing.  Some  of  the  modern  single  and  multi- 
coated  rubberized  silks  are  most  beautiful  and 
serviceable  fabrics,  and  by  many  are  regarded  as 
the  highest  quality  of  all  balloon  materials.  The 
best  silk  balloon  fabrics  come  twenty-seven  inches 
wide  and  at  present  retail  for  from  $2.00  to  $3.50 
a  yard.  An  objection  to  silk  is  its  electrostatic 
properties,  rendering  the  possibility  of  discharges 
sufficient  to  ignite  the  gas  much  more  likely  when 
it  is  used  than  is  the  case  with  cotton  and  linen. 

Cotton,  in  its  best  qualities  (the  sea-island  and 
Egyptian),  is  one  of  the  strongest  and  most  du- 
rable of  all  fabrics,  as  is  particularly  evidenced  in 
its  exclusive  use  in  pneumatic  tires,  in  which  the 
stresses  to  which  it  is  subjected  are  literally  ter- 
rific. It  is,  however,  very  subject  to  weakening 
from  the  action  of  moisture,  the  least  rotting  affect- 
ing it  most  adversely.  In  the  form  of  muslins  and 
percales  it  is  very  strong  and  inexpensive,  but  care 
must  be  taken  to  secure  the  best  grades  of  closely- 
woven,  unsized,  and  unbleached  goods,  if  superior 
results  are  to  be  secured.  Impregnated  with  suit- 


94  VEHICLES  OF  THE  AIR 

able  materials,  it  is  readily  made  fairly  impervious 
to  gases  and  insusceptible  to  weather.  The  best 
rubberized  cotton  balloon  fabrics  come  from  thir- 
ty-six to  forty  inches  wide,  and  cost  from  90  cents 
to  $1.50  a  square  yard. 

Linen  threads  and  fabrics  are  almost  as  strong 
as  silk  and  cotton,  the  long  fiber  making  an 
ordinary  linen  thread  or  cord  stronger  than  any 
but  the  finest  sea-island  cottons.  In  durability 
under  flexing  it  is  superior  to  silk,  though  not 
as  good  as  the  best  cotton.  In  its  resistance  to 
deterioration  from  water,  it  finds  place  between 
cotton  and  silk,  being  superior  to  the  former  and 
inferior  to  the  latter. 

Miscellaneous  Envelope  Materials  are  used  to 
some  extent,  but  the  best  of  these  are  combinations 
of  materials  already  discussed.  Thus  some  high 
grade  balloon  fabrics  consist  of  a  layer  of  rubber 
faced  on  one  side  with  silk  and  on  the  other  with 
cotton,  the  idea  being  to  combine  the  advantages 
of  both  materials.  Several  plies  of  different 
weights  and  materials  can  be  superimposed  in  this 
manner.  Eamie,  jute,  manila,  and  other  fabric 
materials  do  not  possess  the  advantages  of 
commoner  goods. 

Paper — the  jute  manilas,  banknote,  and  parch- 
ment papers,  and  the  tough  papers  that  are  used 
in  Japan  for  clothing — has  been  tried  with  success 
in  balloon  manufacture,  as  is,  indeed,  evident  in 
the  early  work  of  the  Montgolfiers  and  in  modern 
fire  balloons.  Paper  has  the  merit  of  extreme 


FIGURE  12. — Curious  Drag  Rope  of  Wellman  Dirigible. 


FIGURE  14. — Balloon  House  for  the  Dirigible  "Russie"  in  Course  of  Construction. 


LIGHTER-THAN-AIR  MACHINES          95 

cheapness  and  a  considerable  imperviousness,  but 
is  not  durable. 

Goldbeater's  skin,  from  the  caecum  of  the  ox, 
has  been  used  to  some  extent  for  model  and 
" sounding''  balloons,  and  is  exceedingly  light, 
strong,  and  impervious.  Its  great  cost,  the  diffi- 
culty of  strongly  joining  the  many  small  pieces, 
and  its  susceptibility  to  moisture  have  prevented 
its  extensive  use. 

Coating  Materials  that  are  suitable  for  gas- 
proofing  balloon  envelopes  are  very  few  in 
number. 

Vulcanized  rubber  undoubtedly  is  the  most 
impervious  and  is  an  excellent  protection  to  the 
fabric,  but  it  oxidizes  and  cracks  with  age.  Ked 
rubber  coatings  offer  a  maximum  resistance  to 
oxidization  from  the  sun's  rays,  while  gray  rubber 
inner  linings  are  found  most  impervious  to  gases. 

Linseed  oil  varnishes  are  cheap,  slightly  lighter 
than  rubber,  and  easily  reapplied  as  leaks  appear, 
but  tend  to  be  sticky,  especially  when  newly 
applied  or  in  warm  weather,  usually  requiring  lib- 
eral dustings  of  powdered  talc,  soapstone,  or  chalk 
to  keep  a  folded  balloon  envelope  from  sticking 
together.  Besides  this  they  are  rather  susceptible 
to  the  action  of  rain  and  mist. 

Gutta  percha,  dissolved  in  benzine,  has  merits 
in  the  way  of  lightness  and  cleanliness  but  is  rather 
pervious  unless  heavily  applied,  besides  which  it 
may  crack  under  repeated  folding. 

In  addition  to  the  foregoing  well  known  mate- 
rials there  are  various  balloon  varnishes  the  com- 


96  VEHICLES  OF  THE  AIR 

positions  of  which  are  kept  secret  by  the  manu- 
facturers, but  most  of  which  are  of  very  fair  qual- 
ity. Indeed,  to  so  exact  a  science  has  the  manufac- 
ture of  balloon  envelopes  been  reduced,  the  best 
envelope  materials  on  the  market  are  now  guar- 
anteed when  new  not  to  permit  the  escape  of  gas 
faster  than  at  some  stated  rate — ten  liters  to  the 
square  meter  per  twenty-four  hours,  under  thirty 
millimeters  of  water  pressure,  being  the  guaran- 
teed maximum  for  double  sheetings  of  the  qual- 
ities illustrated  in  Figure  7.  Reduced  to  English 
equivalents  this  is  not  quite  TV  cubic  foot  of  gas 
per  square  yard  per  twenty-four  hours,  under  a 
pressure  of  6f  pounds  to  the  square  foot.  In  the 
case  of  a  dirigible  like  the  largest  Zeppelin,  with 
a  surface  of  about  6,300  square  yards  and  a  capacity 
of  about  536,000  cubic  feet,  this  means  a  loss  of 
only  2,000  cubic  feet  of  gas  a  day. 

In  joining  rubberized  envelope  materials,  the 
breadths  are  lapped  an  inch  or  less,  given  three 
successive  coats  of  rubber  cement,  each  of  which 
is  allowed  to  dry,  and  are  then  rolled  tightly 
together  with  a  metal  roller.  This  done,  the  seams 
are  sewed  and  after  sewing  covered  with  adhesive 
strips  of  joining  material,  coated  with  sticky, 
unvulcanized  rubber,  which  also  are  rolled  down 
hard  with  a  metal  roller. 

INFLATION 

Inflation  materials  for  balloons  present  little 
variety  and  few  possibilities  of  improvement. 
Obviously  the  range  is  limited  to  such  gases  as 


FIGURE  15. — Portable  Balloon  House  Used  by  the  French  Army.  This  immense  structure 
is  built  in  easily  assembled  and  dismounted  units,  so  that  it  can  be  hauled  to  a  desired  point 
by  wagon  train  and  quickly  set  up.  Note  the  arch  on  the  ground,  awaiting  erection. 


FIGURE  10. — Balloon    Houses   Nearing   Completion. 


:  '--: 


LIGHTER-THAN-AIR  MACHINES  97 

are  lighter  than  air,  with  reasonable  preference  for 
the  lightest,  though  considerations  of  cost,  avail- 
ability, and  safety  are  not  ordinarily  to  be  dis- 
regarded. 

Heated  Air,  as  has  been  explained,  was  one 
of  the  first  substances  used  for  balloon  inflation. 
Air  expands  about  ^-^  of  its  volume  for  each 
degree  Fahrenheit  increases  in  temperature,  so 
heating  from  60°  F.  to  150°  F—  for  example— will 
increase  the  volume  occupied  by  one  pound  from 
about  13.1  cubic  feet  to  22.7  cubic  feet,  making  the 
contents  of  a  balloon  subjected  to  this  rise  in  tem- 
perature only-Hi  as  heavy  as  the  external  air,  with 
the  result  of  securing  an  ascensional  force  of  ap- 
proximately -^y  pound  for  each  cubic  foot  of  con- 
tents. Of  course,  no  matter  what  the  initial  expan- 
sion given  the  air  it  rapidly  cools  with  removal  of 
the  source  of  heat,  so  to  maintain  a  hot-air  balloon 
in  the  air  for  any  period  of  time  requires  that  there 
be  carried  along  some  means  of  continued  heating 
(see  Page  70).  Because  the  balloons  built  by  the 
Montgolfiers  were  of  the  heated-air  type,  such 
balloons  are  often  called  "montgolfieres." 

In  heating  the  air  in  practical  ballooning  it  is 
not  now  attempted  to  do  this  otherwise  than  on 
the  ground,  before  the  start,  as  hot-air  balloons 
are  chiefly  used  for  brief  ascensions — exhibitions, 
parachute  jumps,  etc. — longer  balloon  voyages 
generally  being  made  with  gas  craft.  The  chief 
essentials  of  a  heating  plant  are  cheapness  or  port- 
ability, and  a  capacity  for  producing  quick  in- 
flation. 


98  VEHICLES  OF  TEE  AIR 

The  simplest  and  at  the  same  time  most  prac- 
tical and  efficient  methods  for  inflating  modern 
heated-air  balloons  involve  little  more  than  digging 
a  trench  in  the  ground,  covering  this,  and  then 
connecting  it  with  the  balloon,  which  is  suspended 
or  partially  suspended  from  a  pole  erected  near 
one  end  of  the  trench.  A  hot  fire  is  maintained 
in  the  end  of  the  trench  farthest  from  the  bal- 
loon by  repeated  supplies  of  light  solid  fuels,  or 
by  dashes  of  gasoline  thrown  with  a  cup.  Suffi- 
cient draft  must  be  provided  to  insure  flow  of  the 
heated-air  through  the  trench  and  into  the  neck  of 
the  balloon. 

Hydrogen  is  the  lightest  of  all  known  sub- 
stances, one  cubic  foot  of  this  gas  at  32°  F. 
and  at  atmospheric  pressure  weighing  only 
.005592  pound,  against  .080728  pound  for  an 
equal  volume  of  air  under  the  same  conditions  of 
temperature  and  pressure.  Hydrogen  is  very  com- 
bustible, burning  readily  in  the  presence  of  air  or 
oxygen,  the  product  of  the  combustion  being 
water  (hydrogen  monoxid).  Mixed  with  air  in 
proper  proportions  it  forms  violently  explosive 
mixtures.  Though  one  of  the  most  abundant  of  all 
the  elements,  it  rarely  is  found  except  in  combina- 
tion with  other  elements.  It  was  first  isolated  by 
Cavendish  in  1766. 

Hydrogen  is  readily  prepared  by  the  decompo- 
sition of  water  or  steam,  electrolytically  or  other- 
wise, and  by  the  action  of  dilute  sulphuric  acid 
upon  zinc  or  iron,  the  latter  reaction  being  still 
much  used  for  the  production  of  this  gas  for  the 


LIGHTER-THAN-AIR  MACHINES          99 

inflation  of  balloons.  It  is  a  chief  constituent  of 
all  the  common  fuel  and  illuminating  gases. 

A  modern  process  for  producing  hydrogen — a 
process  that  is  coming  into  considerable  use  for 
the  inflation  of  military  dirigibles  in  continental 
Europe — is  that  of  Dellwik-Fleischer  for  rapidly 
and  inexpensively  manufacturing  very  pure  hydro- 
gen by  the  reactions  that  ensue  when  steam  is 
passed  through  a  spongy  mass  of  iron  ore,  previ- 
ously partially  reduced  to  metallic  iron  by  the 
action  of  water  gas.  The  process  virtually  may 
be  said  to  be  divided  into  four  stages — the  first 
two  in  alternation  having  to  do  with  the  rapid 
and  economic  production  of  the  necessary  water 
gas  and  the  second  two  in  alternation  affording 
the  hydrogen. 

Beginning  with  the  manufacture  of  the  water 
gas — a  tall  cylinder  is  filled  with  coke  through 
which  heated  air  is  passed  for  about  a  minute, 
causing  sufficient  combustion  to  produce  a  high 
temperature;  then  the  air  is  shut  off  and  steam 
is  passed  through  the  coke  for  about  half  an  hour — 
until  the  temperature  is  so  lowered  that  reheat- 
ing must  be  effected  by  the  air  blast — during  which 
time  the  water  gas  is  produced  from  decomposi- 
tion of  the  steam  by  the  coke  and  admixture  with 
the  resulting  hydrogen  of  a  practically  equal  quan- 
tity of  carbon  monoxid  formed  in  the  process. 
Small  quantities  of  carbon  dioxid,  sulphuretted 
hydrogen,  etc.,  which  also  appear,  are  removed 
before  the  final  two  stages  of  the  process. 

These  final  stages,  which  produce  the  hydrogen, 


100  VEHICLES  OF  THE  AIR 

involve  the  use  of  a  tall  retort  filled  with  hematite 
or  magnetic  iron  ore,  or  with  a  mixture  of  the 
two,  and  surrounded  by  a  furnace  capable  of  main- 
taining the  retort  at  a  temperature  of  about 
1,470°  F.  The  first  stage  consists  in  passing 
through  the  retort  enough  water  gas  to  reduce 
the  ore  to  spongy  iron — the  action  being  stopped 
at  a  point  dictated  by  experience,  and  con- 
siderably short  of  complete  reduction.  The  final 
stage  consists  in  stopping  the  supply  of  water  gas 
and  substituting  for  it  a  flow  of  steam,  which  the 
spongy  mass  of  highly-heated  metal  decomposes 
into  its  elements,  hydrogen  and  oxygen,  the  first 
being  collected  and  the  second  forming  with  the 
iron  a  mass  of  ferric  oxid  which  can  be  again 
reduced  by  the  use  of  water  gas. 

Since  the  raw  materials  required — coke,  iron 
ore,  and  water — all  are  very  cheap,  and  both  the 
water  gas  and  hydrogen  are  produced  intermit- 
tently, the  process  lends  itself  readily  to  econom- 
ical working  and  to  the  use  of  simple  and  reason- 
ably portable  apparatus,  the  latter  involving  little 
more  than  the  cylinder  for  the  coke,  the  retort  and 
furnace  for  the  iron  ore,  a  boiler  to  supply  the 
steam,  and  a  small  gasometer  to  contain  the  water 
gas.  No  special  fuel  is  required  for  the  retort- 
heating  furnace,  the  water  gas  coming  through 
the  iron  ore  without  a  sufficient  loss  of  combustible 
elements  to  preclude  its  use  as  a  source  of  heat 
for  this  purpose. 

The  hydrogen  produced  by  this  process  is  ex- 
ceptionaly  pure — 98J% — containing  only  a  small 


.... 


FIGUBE  17. — The  latest  Zeppelin  Dirigible.  The  upper  picture  shows  the  rigid  construc- 
tion very  clearly,  while  in  the  different  views  the  stabilizing  fins  c,  the  dipping  planes  bb,  and 
the  rear  rudder  a,  are  clearly  shown. 


LIGHTER-THAN-AIR  MACHINES         101 

admixture  of  atmospheric  nitrogen  and  trifling 
quantities  of  other  gases. 

Illuminating  Gases  of  all  the  common  qualities 
are  lighter  than  air  and  therefore  are  of  greater  or 
less  theoretical  utility  for  balloon  inflation.  Prac- 
tically, however,  the  only  ones  available  are  the 
common  coal  and  water  gases  and  natural  gas — 
acetylene  and  olefiant  gas  being  almost  as  heavy 
as  air,  besides  very  expensive,  while  the  pure 
methanes,  pentanes,  etc.,  are  not  only  difficult  to 
prepare  but  when  prepared  present  no  advantages 
over  the  more  complex  compounds  that  are  to  be 
had  by  tapping  the  widely-available  commercial 
mains. 

Ordinary  coal  gas  weighs  about  .03536  pound 
to  the  cubic  foot,  while  heavy  carbureted  hydrogen 
weighs  .04462  pound  to  the  cubic  foot.  Acetylene 
weighs  .0767  pound  to  the  cubic  foot,  and  olefiant 
gas  weighs  .0795  pound  to  the  cubic  foot. 

Though  the  majority  of  commercial  illuminat- 
ing gases  are  complex  and  too  often  very  impure 
compounds,  it  is  a  safe  generalization  that  as  taker- 
from  the  mains  for  balloon  use  they  can  be  counted 
upon  to  afford  ascensional  forces  equal  to.  froix) 
nine  to  seven-sixteenths  of  the  weight  of  the  air 
displaced. 

Most  natural  gas  is  fairly  pure  methane,  and 
is  light  enough  to  serve  very  well  for  balloon 
inflation. 

Vacuum  chambers  as  means  of  securing  ascen- 
sional force  are  from  time  to  time  resuggested  by 
deluded  inventors,  but  since  this  principle  is  pos- 


102  VEHICLES  OF  THE  AIR 

sibly  the  first  ever  produced  for  balloon  construc- 
tion, besides  which  it  is  as  unavailable  as  it  is 
ancient,  it  need  be  mentioned  only  to  be  dismissed. 
All  that  there  is  to  be  said  on  the  subject  is  pretty 
thoroughly  analyzed  in  the  consideration  of  friar 
Lana's  copper-plated  vacuum,  on  Page  67. 

Miscellaneous  inflation  possibilities  undoubt- 
edly exist  in  the  prospect  of  new  gases  to  be  dis- 
covered or  in  the  utilization  of  ones  now  known  but 
not  employed,  but  whatever  the  advantages  thus 
left  to  be  secured  it  is  certain  that  among  them 
there  will  not  be  any  material  increase  in  lifting 
capacity,  since  hydrogen  already  affords  nearly 
41  of  all  the  lift  there  is  to  be  had,  this  factor  be- 
ing limited,  as  has  been  previously  emphasized,  not 
by  the  lightness  of  gases,  but  by  the  weight  of  air 
displaced.  However,  should  helium,  which  is 
almost  as  light  as  hydrogen  (11  units  of  lifting 
capacity  against  12  with  hydrogen),  ever  be 
commercially  produced  in  quantity  it  is  possible 
that  it  would  be  of  advantage  to  use  it  because  of 
ite:  c-hemical  inertness,  which  in  general  as  well  as 
military  uses  certainly  would  contrast  favorably 
vhfth  -the  dangerous  inflammability  of  hydrogen. 
At  the  present  time  practically  all  the  isolated 
helium  in  the  world  is  the  quantity  of  about  14J 
cubic  feet  in  the  possession  of  the  University  of 
Leyden.  Ammonia  gas,  which  is  almost  as  light 
as  some  illuminating  gases — .04758  pound  to  the 
cubic  foot — might  appear  to  have  some  possible 
application  to  the  inflation  of  balloons  designed  to 
be  proof  against  incendiary  projectiles.  Its  cost, 


LIGHTER-THAN-AIR  MACHINES         103 

difficulty  of  preparation  with  present  portable 
facilities,  its  extremely  irritating  effect  when 
respired,  even  in  very  small  quantities,  and  its 
deleterious  action  on  envelope  coatings,  are  among 
the  greatest  objections  to  it. 

NETTINGS 

Nettings  are  necessary  in  all  the  non-rigid  types 
of  balloons  to  restrain  the  gas  bag  to  its  proper 
form  and  to  distribute  the  load  of  car  and  cargo 
uniformly  over  it.  To  meet  these  requirements, 
cordage  of  very  high  strength  is  usually  employed 
for  nettings,  knotted  into  meshes  varying  with 
the  size  of  balloon,  the  weight  supported,  and  the 
strength  of  the  fabric,  but  always  sufficiently  close 
to  insure  uniform  distribution  of  the  stresses  and 
to  prevent  serious  accident  from  local  breakages. 
Very  often  the  nets  used  are  of  closer  mesh  over 
the  upper  parts  of  the  gas  bags  than  they  are  lower 
down,  and  they  are  not  usually  made  to  come  very 
much  lower  than  the  median  line  of  a  balloon,  as 
in  Figure  8,  in  which  a  typical  modern  spherical 
balloon  is  well  illustrated,  all  of  the  weight  being, 
of  course,  sustained  upon  the  upper  part.  In  this 
illustration,  a  indicates  the  lower  edge  of  the  net- 
ting, from  which  a  series  of  straight  cords  are  used 
to  connect  it  directly  with  the  car.  The  large 
number  of  these  and  their  practical  independence 
of  one  another  is  in  the  ordinary  balloon  a  chief 
safeguard  against  structural  disaster. 

Balloon  nettings  are  usually  knotted  exactly 
the  same  as  common  fish  nets,  preferred  forms  of 


104 


VEHICLES  OF  THE  AIR 


knots  employed  and  the  wooden  shuttles  used  for 
making  them  being  illustrated  in  Figure  9. 


FIGURE  9. — Shuttles  for  Knotting  Balloon  Nettings,  and  some  Typical  Knots 

Decidedly  unusual,  yet  not  without  some 
merits,  was  the  use  of  piano  wire  in  the  place  of 
cord  supports  in  the  Santos-Dumont  dirigible  "No. 
6"  and  in  the  ill-fated  Servero  balloon  (see  Page 
107) .  The  merit  of  wire,  besides  the  great  strength 
and  lightness,  is  its  small  resistance  to  movement 
through  the  air. 

CAR  CONSTRUCTION 

It  becomes  obvious  upon  a  most  casual  con- 
sideration or  investigation  of  the  subject  that 
unending  variety  of  designs  and  systems  of 
construction  are  possible  in  the  devising  of  bal- 
loons and  balloon  cars.  This  being  the  case,  no 
attempt  is  made  herein  to  describe  all  possible 
forms,  it  being  enough  to  note  a  few  general  prin- 
ciples that  must  always  prevail,  together  with 
some  comment  on  the  most-used  materials.  Natu- 


t 


a 


FIGURE  18. — Dirigible  Balloon  "Ville  de  Nancy." 


FIGURE  21. — Malicot  Semi-Rigid  Dirigible  Balloon. 


FIGURE  22. — Nacelle  of  the  French  Dirigible  ;'Zodaic  III.' 


LIGHTER-THAN-AIR  MACHINES         105 

rally,  the  conservative  and  well  informed  investi- 
gator will  be  largely  influenced  by  even  though 
he  may  not  closely  follow  the  constructions  of 
others  who  have  pioneered  this  field.  Many  of 
these  constructions  are  described  or  illustrated 
herein  in  connection  with  the  descriptions  of  the 
balloons  to  which  they  pertain.  It  may  be  to  the 
point,  however,  here  to  call  attention  to  the  fact 
that  dirigible  balloon  cars,  besides  serving  pri- 
marily for  the  accommodation  of  passengers  must 
also  often  serve  as  mounting  and  bracing  for  motor 
and  propelling  means,  and,  in  the  case  of  semi- 
rigid dirigibles,  as  stiffening  members  for  preserv- 
ing the  shape  of  the  gas  bag. 

Rattans  of  the  kinds  commonly  employed  in 
wicker  and  basket  work  have  found  extensive  use 
in  the  manufacture  of  ordinary  balloon  cars,  to  the 
construction  of  which  they  are  eminently  adapted 
by  reason  of  their  lightness,  strength,  and  ease 
of  working.  For  the  more  elaborate  cars,  or 
"nacelles",  of  dirigibles,  they  prove  less  suitable, 
it  being  difficult  to  make  such  elongated  structures 
as  this  type  generally  requires  without  the  use  of 
heavier  and  stiffer  materials. 

Wood  is  the  preferred  material  for  building 
the  understructures  of  modern  non-rigid  and  semi- 
rigid dirigible  balloons,  and  is  coming  to  be  re- 
garded as  superior  to  metal  for  the  framing  of 
balloons  of  the  rigid  type,  such  as  the  Zeppelin. 
Of  the  different  woods,  bamboo,  spruce,  etc.,  are 
generally  regarded  as  the  most  suitable  (see 
Chapter  11).  The  nacelles  of  several  typical 


106  VEHICLES  OF  THE  AIR 

dirigibles  are  shown  in  considerable  detail  in 
Figures  18,  19,  20,  21,  and  22.  That  of  the  Well- 
man  balloon  is  largely  of  steel. 

As  will  be  noted  from  an  examination  of  these 
illustrations,  metal  joining  members  and  corner 
pieces  are  used  in  most  cases,  with  diagonal  stay- 
ing with  wire. 

Miscellaneous  schemes  and  materials  of  car 
construction  are  disclosed  from  time  to  time  in  the 
design  of  new  dirigibles,  and  often  new  details  of 
considerable  interest  thus  appear.  Besides  the 
common  use  of  wire  diagonals  and  metal  corner 
members,  already  referred  to,  cordage,  leather, 
and  rawhide  lashings  have  their  special  merits 
and  special  applications,  as  is  more  fully  explained 
in  Chapter  11.  Covering  materials,  such  as 
leather,  canvas,  thin  wood,  and  ordinary  balloon- 
envelope  fabrics  often  are  applied  to  balloon  cars 
to  reduce  wind  resistance,  shelter  the  passengers, 
or  add  to  apearance. 

HEIGHT  CONTROL 

The  control  of  height  is  a  balloon  problem 
involving  a  number  of  well-established  factors  and 
admitting  of  a  considerable  variety  of  solutions. 
The  atmosphere  varying  in  its  density  and  conse- 
quent sustaining  quality  with  every  variation  in 
barometric  pressure,  whether  due  to  variation  in 
altitude  or  variation  in  meteorological  conditions, 
it  follows  that  to  navigate  a  balloon  either  up  or 
down  must  involve  either  a  change  in  the  quantity 
of  sustaining  gas  or  in  the  weight  to  be  sustained, 


LIGHTER-THAN-AIR  MACHINES         107 

or  must  require  the  application  of  power  to  operate 
against  the  normal  tendency  to  float  at  some  cer- 
tain level  determined  by  the  interaction  of  the 
various  factors  of  barometric  pressure,  weight, 
ascensional  force,  etc. 

Non-Lifting  Balloons,  so-called,  are  ones  in 
which  balance  of  the  weight  and  ascensional  force 
is  provided  at  the  ground  level,  instead  of  at  some 
greater  height,  as  is  virtually  the  case  with  ordi- 
nary balloons.  This  balance  accomplished,  it  has 
been  sought  to  travel  up  and  down  by  the  supple- 
mentary action  of  one  or  more  propellers  revolving 
in  a  horizontal  plane,  the  idea  being  that  no  matter 
how  slight  the  propeller  thrust  it  must  be  sufficient 
to  produce  the  vertical  movement.  The  fallacy 
of  this  reasoning  becomes  apparent  when  it  is  con- 
sidered that  the  required  initial  equilibrium  can 
exist  only  at  some  given  level  and  therefore  is 
lost  immediately  upon  ascent  or  descent  to  any 
higher  or  lower  level.  As  well  expect  to  draw  a 
balloon  in  equilibrium  at  a  height  down  to  the 
ground  by  a  propeller  as  to  expect  to  raise  to  a 
height  one  in  equilibrium  at  the  ground.  The 
thing  can  be  done,  of  course,  but  its  accomplish- 
ment loses  all  practical  value  in  the  complication 
and  precariousness  of  the  resulting  conditions.  It 
was  in  a  balloon  of  this  type  that  Auguste  Servero 
and  his  engineer  Sachet  lost  their  lives  in  France, 
on  May  12, 1902. 

Escape  Valves  of  one  sort  or  another,  for  dis- 
charging more  or  less  of  the  gas,  are  the  time- 
established  means  of  causing  a  balloon  to  descend. 


108 


VEHICLES  OF  THE  AIR 


Such  valves  usually  are  of  very  large  diameter 
and  are  located  in  the  highest  part  of  the  gas  bag, 
with  control  by  means  of  a  cord  running  down 
within  reach  of  the  operator's  hand.  Originally 
devised  by  M.  Charles  (see  Page  71),  escape  valves 
have  changed  but  little  from  the  form  finally 
decided  upon  by  him  as  most  satisfactory.  One 
of  modern  construction  is  illustrated  in  Figure  10, 
in  which  a  &  is  a  double  wood  ring  between  which 
the  edges  of  the  fabric  at  the  top  of  the  balloon 

are  clamped,  while 
c  is  a  cover  to  the 
opening  in  a  &,  nor- 
mally held  up  by 
the  gas  pressure 
and  the  spring 
hinges  d  d  d  d,  but 
arranged  to  pull 
down  as  shown  by 
the  rope  e,  when  it 
is  desired  to  permit 
the  escape  of  gas. 

P  r  a  c  t  i  cally  a 
valve   is   the   "rip 

quantity  of  gas.  cord,"  by  means  of 

which  a  seam  running  along  the  side  of  a  bal- 
loon can  be  laid  open.  The  "rip  cord"  finds  its 
use  just  at  the  moment  of  landing,  as  a  means  of 
quickly  collapsing  the  gas  bag  before  it  can  be 
blown  about  by  the  wind,  or  caused  to  reascend  by 
losing  the  weight  of  the  passengers. 


FIGURE  10. — Balloon  Valve.  The  fab- 
ric at  the  top  of  the  gas  bag  Is  clamped 
between  the  rings  a  b,  and  the  opening 
through  these  rings  is  kept  normally 
closed  by  the  disk  c,  held  in  place  by 
the  pressure  of  the  gas  and  the  tension 
of  the  spring  hinges  d  d  d  d,  but  a  pull 
on  the  cord  e  serves  to  open  the  valve, 
permitting  the  escape  of  any  desired 


FIGURE  19.— Side  View  of  Nacelle  of  Wellman  Dirigible. 


FIGURE  20. — Front  View  of  Nacelle  of  the  Wellman  Dirigible.  The  driving  system  is 
well  shown  in  this  illustration,  from  which  it  is  evident  that  the  transmission  is  one  that 
might  readily  be  applied  to  an  aeroplane.  The  motor  is  set  crosswise  of  the  car,  its  prolonged 
crankshaft  driving  the  twin  propellers  oppositely  by  bevel  gears  contained  in  the  housings  era. 


LIGHTER-THAN-AIR  MACHINES         109 

Ballast,  by  the  discharge  of  which  ascension 
can  be  induced,  is  another  early  method  of  height 
control,  and  in  alternation  with  discharge  of  gas 
still  is  found  a  most  effectual  means  of  controlling 
vertical  movement.  Fine  clean  sand  is  generally 
preferred  as  ballast,  as  calculated  to  cause  the  least 
injury  to  anything  upon  which  it  may  fall.  Such 
sand  as  is  commonly  used  will  weigh  from  90  to 
117  pounds  to  the  cubic  foot.  Water,  which  weighs 
63.35  pounds  to  the  cubic  foot,  has  been  employed, 
and  has  the  advantage  of  breaking  into  impercep- 
tible mist  before  it  falls  very  far,  but  the  necessity 
for  cans  or  tanks  to  contain  it  is  a  great  objection, 
since  these  cannot  be  cast  overboard  as  carelessly 
as  may  be  the  sacks  used  to  contain  sand.  Bags 
of  ballast  usually  are  carried  hung  around  the 
edges  of  a  balloon  car,  as  at  a  a,  Figure  11.  It  has 
been  proposed  to  carry  water  in  canvas  bags. 

With  a  balloon  of  moderate  size  the  discharge 
of  even  a  most  trifling  weight  of  ballast  often  pro- 
duces an  astonishing  change  in  height,  the  drop- 
ping of  a  lead  pencil  having  been  observed  to  cause 
an  ascent  of  a  hundred  feet.  In  emergencies, 
clothing,  instruments,  etc.,  often  have  been  cast 
away  as  ballast,  and  there  are  instances  in  the 
history  of  ballooning  in  which  the  basket  itself 
has  been  cut  loose,  the  passengers  clinging  to  the 
netting  cords. 

Compressed  Gas,  carried  in  cylinders  and  per- 
mitted to  escape  into  the  balloon  and  there  expand, 
or  drawn  out  and  recompressed,  serves  to  control 
height  in  a  very  scientific  manner.  Not  only  is 


110  VEHICLES  OF  THE  AIR 

the  sustaining  force  reduced  by  the  withdrawal  of 
a  portion  of  the  gas  from  the  envelope,  but  this 
gas  compressed  serves  the  purpose  of  ballast.  The 
chief  objections  to  this  system  inhere  in  the  weight 
of  the  containers  required  for  the  compressed  gas 
and  in  the  power  necessary  for  compression. 

Drag  Ropes  can  be  used  in  certain  circum- 
stances as  a  sort  of  recoverable  ballast.  Thus  with 
a  long  rope  trailing  on  the  ground  it  is  evident  that 
if  for  any  reason  the  balloon's  lifting  capacity 
decreases,  as  from  condensation  of  moisture  upon 
the  envelope,  etc.,  the  consequent  descent  will 
reduce  the  weight  as  more  and  more  of  the  rope 
rests  upon  the  ground  until  a  condition  of  equi- 
librium is  reached.  Conversely,  should  the  balloon 
start  to  ascend,  the  increasing  weight  of  rope  it 
picks  up  must  finally  stop  it.  This  system  works 
best  only  with  very  long  or  heavy  drag  ropes  and 
is  obviously  inapplicable  over  rough  or  thickly- 
populated  country.  One  of  the  most  interesting 
applications  of  this  principle  was  that  planned  for 
the  Wellman  dirigible,  with  which  it  was  planned 
to  seek  the  North  Pole.  In  this  application  the 
drag  rope,  made  of  a  leather-casing,  was  filled  with 
provisions  and  supplies  and  armored  with  steel 
scales  to  withstand  the  wear  of  the  continued  drag- 
ging. The  details  of  its  appearance  are  shown  in 
Figure  12.  Unfortunately,  it  broke  on  the  first 
attempt  to  use  it,  in  August,  1909. 

Open  Necks,  or  incomplete  inflation  of  balloon 
envelopes,  are  necessary  to  provide  for  the  expan- 
sion of  the  gas  that  takes  place  as  the  balloon 


LIGHTER-THAN-AIR  MACHINES        111 

ascends  from  a  level  of  high  barometric  pressure 
to  one  of  lower  air  pressure,  or  that  results  from 
changes  in  temperature.  With  a  gas  bag  com- 
pletely filled  and  no  provision  for  the  gas  to  escape, 
this  tendency  to  expand  will  cause  a  bursting  of 
the  envelope  with  consequent  disaster,  as  soon  as 
a  sufficient  pressure  is  attained.  With  large 
dirigible  balloons,  especially  those  built  on  sec- 
tional plans,  incomplete  inflation  of  the  gas-con- 
taining units  is  preferred  to  the  use  of  open  necks, 
since  the  latter  permit  a  gradual  but  no  less  free 
mingling  of  the  gas  with  the  external  air.  A  dan- 
ger to  be  guarded  against  in  the  design  of  open- 
neck  balloons  is  that  of  placing  the  car  so  close  to 
the  opening  as  to  expose  the  passengers  to  the  risk 
of  complete  or  partial  asphyxiation  from  prolonged 
escape  of  gas. 

Internal  Balloons,  filled  with  air  kept  at  a  con- 
stant pressure  by  some  sort  of  continuously-acting 

blower  device,  have  been 
very  successfully  used 
in  many  modern  dirig- 
ibles, notable  among 
them  being  that  with 


FIGUB*     13.-lnternal      Balloon, 

2S  with™?  eflmnsopit°sfodfui!lb0ef     won  the  Deutsch  prize 

gas  that  some  must  escape  in  case         .        -if\f\~t      /  -r*  <^r»\ 

of  expansion.     With  this  construe-        in    1901     (866    Pa£6    82), 
tion,   expansion   of   the   gas   simply 

KSP$R!^£  ^ttZt&rS     to  ke*P  the  external  en- 

velop tight  without  the 

use  of  the  open-neck  scheme  and  in  spite  of  insuf- 
ficient inflation.  With  this  construction  expansion 
of  the  gas  simply  compresses  the  internal  balloon 


112  VEHICLES  OF  THE  AIR 

and  expels  a  portion  of  the  air  from  it,  but  with- 
out altering  the  pressure  that  it  is  sought  to  main- 
tain throughout  the  entire  envelope.  A  diagram 
of  a  dirigible  built  on  this  design  is  given  in  Figure 
13,  in  which  the  main  gas  bag  encloses  the  internal 
balloon,  with  the  blower  in  the  car  below. 

Moisture  condensed  upon  the  surface  or  ab- 
sorbed by  the  material  of  a  balloon  envelope  has  a 
marked  effect  in  causing  it  to  descend — partly 
because  the  quantity  of  water  thus  condensed  is 
by  no  means  slight,  and  partly  because  it  only 
requires  a  very  slight  addition  of  weight  to  occa- 
sion a  considerable  descent.  A  film  of  water  only 
•^  inch  thick  over  the  entire  envelope  surface 
of  one  of  the  great  Zeppelin  dirigibles,  for  example, 
adds  over  half  a  ton  to  the  weight.  As  for  the 
effect  of  moisture  actually  absorbed,  one  manufac- 
turing concern,  which  produces  a  particularly  ex- 
cellent balloon  fabric  weighing  9.5  ounces  to  the 
square  yard,  guarantees  that  the  increase  in  weight 
from  exposure  to  an  atmosphere  of  maximum 
humidity  will  not  exceed  .38  ounce  to  the  square 
yard. 

Temperature  also  has  marked  effects  upon  the 
sustentional  capacity  of  balloons,  a  very  small 
increase  in  temperature  being  sufficient  to  enchance 
the  lift  very  materially,  while,  conversely,  cooling 
of  the  gas  shrinks  it  enough  to  make  it  lose  much 
of  its  ascensional  force.  In  the  use  of  balloons  it 
often  has  been  noticed  that  drift  into  the  shadow 
of  a  dark  cloud  will  cause  a  descent  perhaps  of 


LIGHTER-THAN-AIR  MACHINES         113 

hundreds  of  feet,  with  a  corresponding  rise  upon 
coming  into  the  bright  sun  again. 

STEEEING 

Steering  a  dirigible  is  easily  effected  by  the 
manipulation  of  rudders,  provided  the  speed  of  the 
craft  through  the  air  is  sufficient  to  set  up  reac- 
tions of  sufficient  magnitude  from  the  air  flow. 
For  slow-moving  airships  larger  rudders  are  re- 
quired than  suffice  for  fast-moving  craft.  Refer- 
ence to  Figures  17, 18,  21  and  22  will  afford  a  clear 
idea  of  the  rudder  schemes  employed  in  modem 
dirigibles.  In  addition  to  the  pivoted  and  mov- 
able rudders  a  and  &  in  these  illustrations,  sta- 
tionary fins  c  also  are  much  used,  to  help  keep  an 
airship  to  its  course,  and  to  reduce  spinning  when 
it  is  not  under  way.  And  in  some  vessels  it  has 
been  proposed  to  effect  steering  by  other  than 
rudder  schemes  for  shifting  the  whole  gas 
bag  around  by  swinging,  skewing,  or  tilting 
movements. 

Lateral  Steering  is  so  readily  effected  by  prop- 
erly designed  vertical  rudders,  such  as  are  marked 
a  in  Figures  17, 18,  21,  and  22,  of  sizes  proportioned 
to  the  speeds  and  sizes  of  the  craft  they  are 
intended  to  control,  that  experiment  with  more 
complicated  schemes  seems  scarcely  worth  while. 
Nevertheless  considerable  attention  has  been  given 
to  devices  for  swinging  the  main  propellers  side- 
wise,  and  even  to  designs  in  which  small  side  pro- 
pellers are  provided  for  pulling  the  whole  vehicle 
around.  Seemingly  ill-advised  on  their  face,  such 


114  VEHICLES  OF  THE  AIR 

systems  of  control  so  far  have  met  with  no  practical 
success. 

In  planning  the  steering  of  a  dirigible,  it  is 
necessary,  if  non-rigid  or  semi-rigid  construction 
be  employed,  to  allow  for  the  flexibility  of  the 
structure  and  also  to  make  sure  that  the  steering 
effect  shall  not  twist  the  car  away  from  its  fasten- 
ings to  the  gas  bag. 

In  steering  an  ordinary  balloon  by  a  drag  rope, 
the  rope  is  simply  moved  from  time  to  time  as  its 
reattachment  revolves  the  balloon.  By  this  scheme 
it  is  possible  to  produce  only  a  slight  angular 
deviation  from  a  straight  drifting  course. 

Vertical  Steering,  by  means  of  horizontal  fins 
or  rudders,  as  shown  at  &  and  c  in  Figures  17,  18, 
and  21,  is  used  in  some  dirigibles  with  consider- 
able success  as  means  of  changing  height  without 
recourse  to  the  discharge  of  gas  or  ballast.  Used 
for  this  purpose  the  effectiveness  of  fins  and  rud- 
ders is  dependent  upon  the  rate  of  longitudinal 
progress  maintained  through  the  air,  as  they 
obviously  can  be  of  no  effect  when  the  balloon  is 
at  rest  or  merely  drifting.  Two  chief  systems  of 
height  control  on  this  principle  are  in  use.  In  one 
the  horizontal  surfaces  are  inclined  up  or  down 
as  direct  steering  means,  while  in  the  other  the 
whole  airship  is  tilted  longitudinally  by  shifting 
of  weight  or  gas,  in  which  condition  fixed  fins  serve 
to  produce  the  required  change  in  level  under  the 
influence  of  longitudinal  propulsion. 

It  is  said  that  one  of  the  Zeppelin  airships, 
during  the  week  of  March  7,  1909,  ascended  to 


LIGHTER-THAN-AIR  MACHINES         115 

an  altitude  of  5,643  feet,  and  descended  again  "  en- 
tirely with  the  use  of  the  elevators",  and  without 
discharge  of  ballast.  The  secrecy  maintained  by 
those  concerned  in  the  Zeppelin  trials  has  pre- 
vented any  definite  confirmation  of  this  statement, 
which  if  correct  is  of  considerable  importance 
in  its  bearings  upon  practical  maneuvering  and 
conservation  of  gas  supply. 

BALLOON  HOUSING 

The  problem  of  properly  housing  large  balloons 
when  they  are  not  in  use,  so  as  to  protect  them 
from  wind  and  weather,  is  a  very  serious  one. 
Because  of  its  great  bulk  any  balloon,  no  matter 
how  stoutly  constructed,  is  essentially  fragile 
when  fastened  to  the  ground  and  exposed  to  the 
buffeting  even  of  moderate  gales.  In  the  air,  of 
course,  the  only  effect  of  wind  is  to  cause  a  drift 
relative  to  the  earth's  surface  but  not  to  the  sur- 
rounding atmosphere.  On  the  ground,  however, 
restrained  from  drifting  by  rope  or  other  attach- 
ments, the  effect  of  even  a  light  wind  is  to  press 
the  gas  bag  over  and  pound  it  upon  the  ground. 
These  considerations  render  imperative  the  pro- 
vision of  proper  housing  of  some  sort.  And,  such 
housings  being  necessarily  very  large  and  sub- 
stantial, and  preferably  inexpensive  enough  to 
permit  of  extensive  placing,  it  is  clear  that  the 
question  of  their  design  is  one  to  tax  the  best  of 
architectural  abilities  and  structural  methods. 

Sheds  for  housing  balloons  and  aeroplanes — 
the  "hangars"  of  the  French  aeronauts  and  avi- 


116  VEHICLES  OF  THE  AIR 

ators,  who  bid  fair  to  fix  this  term  upon  the  Eng- 
lish language — have  been  designed  in  a  great  vari- 
ety of  forms.  The  construction  of  the  best  of  these 
will  be  easiest  appreciated  by  reference  to  Figures 
14,  15,  and  16,  of  which  Figure  14  shows  one 
building  for  the  dirigible  "Russie",  while  Figures 
16  and  17  show  the  Clement-Bayard  portable 
balloon  house  with  which  the  French  army  is 
experimenting. 

Landing  Pits  have  been  proposed  as  substitutes 
for  balloon  sheds,  over  which  they  possess  the 
advantages  of  lower  cost  and  readier  improvisa- 
tion. In  a  characteristic  balloon  pit  the  essential 
feature  is  the  simple  excavation  in  the  earth,  large 
enough  to  shelter  wholly  or  partly  the  air  craft  it 
is  designed  to  protect.  The  scheme  has  been  tried, 
and  possesses  many  features  of  merit,  of  cover- 
ing shallow  excavations  with  low  sheds,  thus 
in  a  measure  combining  the  virtues  of  both 
constructions. 


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CHAPTEE  THREE 

HEAVIER-  THAN-AIK  MACHINES 

The  idea  of  machines,  heavier  than  air,  which 
should  nevertheless  sustain  themselves  in  the  air 
by  the  operation  of  suitable  mechanism,  is  an 
obvious  deduction  from  the  observation  of  the 
birds  and  of  flying  animals  and  insects,  all  of 
which,  quite  without  exception,  are  vastly  heavier 
than  the  tenuous  medium  that  so  securely  supports 
them.  As  a  consequence,  the  earliest  conceptions 
of  heavier-than-air  flying  machines  long  antedate 
the  discovery  of  the  balloon,  even  the  various 
myths  and  apocryphal  accounts  of  flying  men, 
which  have  come  down  from  ancient  times,  being 
invariably  founded  upon  one  or  another  of  the 
obvious  modifications  of  the  mechanical-bird  idea. 
In  later  times,  and  as  science  and  invention 
have  progressed,  attempts  innumerable  have  been 
made  to  construct  successful  machines,  but  with 
results  so  uniformly  discouraging  that  the  very 
term  " flying  machine"  had  become  a  synonym  for 
all  that  was  wild  and  erratic  in  inventors'  brains 
and  mechanical  perversity.  However,  complete 
failures  though  all  the  ideas  of  the  early  air  navi- 
gators proved  when  put  to  the  test,  in  the  revealing 
light  of  more  recent  successes  it  begins  to  appear 
that  past  failures  were  due  less  to  insuperable 

117 


118  VEHICLES  OF  THE  AIR 

obstacles  than  to  incomplete  knowledge — to  a 
failure  to  understand  the  essential  importance  of 
a  very  few  but  most  fundamental  principles. 

The  result  is  that  now,  as  knowledge  is  accumu- 
lated and  tested  and  tabulated  in  every-increasing 
increments,  and  as  the  great  principles  are  com- 
mencing to  be  wrung  from  the  mazes  of  indiffer- 
ence and  skepticism  and  ignorance  that  had  so 
long  concealed  them,  the  aerial  vehicle  is  surely 
and  inevitably  issuing  from  the  mists  of  doubt 
into  the  realms  of  the  practical. 

Of  the  many  varieties  of  heavier -than-air 
machines  that  have  been  constructed  or  con- 
ceived, nearly  all  fall  into  one  or  another  of  three 
basic  classifications — ornithopters,  helicopters,  and 
aeroplanes. 

ORNITHOPTERS 

The  term  ornithopter  embraces,  as  its  name 
implies,  any  type  of  flying  machine  modeled  upon 
the  flapping  or  vibrating  action  of  bird  and  insect 
wings.  Evidently,  the  ornithopter  being  suggested 
by  all  common  types  of  birds,  it  almost  certainly 
preceded  all  other  conceptions  in  mankind's  won- 
derful and  ages-long  development  of  the  art  of 
flying. 

HISTORY 

Possibly  the  earliest  plausible  suggestion  in 
recorded  history  of  a  machine  really  capable  of 
flying  is  the  Aulus  Gellius  reference  to  the  flying 
dove  of  Archytas,  of  which  it  is  gravely  asserted 


HEAVIER-THAN-AIR  MACHINES        119 

"It  was  built  along  the  model  of  a  dove  or  pigeon 
formed  in  wood,  and  so  contrived  as  by  a  certain 
mechanical  art  and  power  to  fly;  so  nicely  was  it 
balanced  by  weights  and  put  in  motion  by  hidden 
and  enclosed  air."  From  this  most  authorities 
conclude  that  Archytas'  machine  was  a  more  or 
less  successful  ornithopter  model,  but  to  the  writer 
it  seems  that  there  is  just  a  suggestion,  in  the 
"balanced  by  weights  and  put  in  motion  by  hidden 
and  enclosed  air",  that  the  ingenious  Archytas 
might  conceivably  have  demonstrated  no  more 
than  the  flotation  of  some  sort  of  oddly-shaped 
and  altogether  premature  toy  balloon — surely 
enough,  at  this,  for  a  man  to  achieve  so  long  in 
advance  of  his  time. 

Even  antedating  the  now  unappraisable  story 
of  Archytas  is  the  seemingly  utter  myth  of  Daeda- 
lus and  Icarus,  who,  Grecian  mythology  main- 
tains, undertook  to  fly  over  the  five  hundred  odd 
miles  of  the  Mediterranean  that  separate  Crete 
from  Sicily.  If  the  "wax "-attached  wings  were 
made  at  all  and  were  made  to  flap,  here  undoubt- 
edly was  the  original  ornithopter,  but  all  of  the 
probabilities  of  the  exploit  are  rather  discounted 
by  the  mythical  form  of  the  story  and  by  the  fur- 
ther fact  that  it  required  a  matter  of  several 
thousand  years  of  progress  to  enable  Bleriot  and 
Latham  to  reenact  the  respective  roles  over  a  much 
shorter  distance. 

Coming  down  to  modern  times  and  passing  by 
without  consideration  various  unauthenticated  or 
less  successful  ornithopters,  with  accounts  of 


120  VEHICLES  OF  THE  AIR 

which  mechanical  history  commencing  with  the 
middle  ages  is  not  infrequently  embellished,* 
possibly  the  first  ornithopter  really  to  produce 
measurable  sustention  was  that  of  Degen,  who 


FIGURE  24. — Degen' s  Orthogonal  Flier. 


in  1809  rose  to  a  height  of  54  feet  by  violently 
flapping  the  deeply-concave  wings  illustrated  in 
Figure  24,  which  totaled  116  square  feet  in  area 
and  were  covered  with  taffeta  bands  arranged  to 
afford  a  valvular  action  similar  to  that  of  the 
feathers  of  the  bird's  wing.  Most  accounts  of  the 


*  Among  the  more  interesting  of  these  accounts  are  those  concerning 
the  construction  proposed  by  Leonardo  da  Vinci,  the  sound  reasoning  of 
Borelli,  the  mishap  that  befel  the  tight-rope  dancer  Allard,  the  seemingly 
interesting  but  now  lost  mechanism  of  Besnier,  the  unfortunate  descent 
of  the  Marquis  de  Bacqueville  into  the  washerwoman 's  barge  in  the 
Seine,  the  failure  of  the  Abbe"  Des forges,  the  flying  chariot  of  Blanchard 
the  balloonist,  the  feathering  wings  of  Bourcart,  the  figure-eight  action 
of  Dandrieux*  machine,  the  Gibson  feathering  wings,  the  early  explosion 
engine  and  the  magnified  stag  beetle  of  Quartermain,  the  Cayley 
umbrella  machine,  the  parachute-and-wing  combination  in  which  Letur 
met  his  death,  the  similar  device  of  De  Groof  that  also  proved  fatal  to 
its  inventor,  the  proposed  Meerwein  apparatus,  the  Breant  artificial  bat, 
the  first  attempt  of  Le  Bris,  the  very  wild  Gerard  project,  the  unsuccess- 
ful Artingstall  model,  the  multi-wing  craft  of  Struve  and  Teleschiff,  the 
Palmer  wing  action,  the  Kaufmann  ornithopter  propulsion,  the  Jay 
model,  the  fairly  successful  steam  toy  of  the  Leipsic  optician,  the 
Prigent  dragon  fly,  the  important  Jobert  and  Penaud  introduction  of 
rubber-band  propulsion  with  the  result  of  producing  successful  models, 
the  subsequent  improvements  in  flying  models  by  Pichancourt,  the  De 
Louvrie  fiasco,  the  Quinby,  Lamboley,  Murrell,  Keith,  Green,  Baldwin 
and  Wheeler  patents,  the  Button,  Pettigrew,  and  Marey  observations,  the 
Frost  steam  bird,  the  45-foot  Moore  bat,  the  original  beating-wing 
machine  of  Ader,  and  the  Napier,  Smyth,  Alexander,  De  Labouret,  Tatin, 
Eichet,  Chanute,  and  other  calculations,  all  of  which  are  interestingly 
treated,  at  the  cost  of  much  research  and  labor,  in  Chanute  ;s  book, 
"Progress  in  Flying  Machines, ft  published  in  1891-1894. 


HEAV1ER-THAN-A1R  MACHINES         121 

Degen  appartus  omit  to  state  that  it  lifted  only 
70  of  the  160  pounds  of  operator  and  machine, 
the  other  90  pounds  being  balanced  by  a  small 
balloon  or  a  counterweight  a^ached  to  a  rope  pass- 
ing over  a  pulley.  Therefore,  considerable  though 
Degen 's  success  really  was,  it  actually  indicated 
man's  inability  rather  than  any  ability  to  fly  by 
his  own  muscular  efforts  applied  to  an  orthogonal 
mechanism. 

Among  those  that  came  after  the  Degen 
machine,  one  of  the  most  interesting  was  the  excep- 
tionally ingenious  Trouve  model,  illustrated  and 


FIGURE  25. — Trouve's  Flapping  Flier.  In  this  machine  the  two  wings,  A. 
and  B,  are  connected  together  by  a  flattened  tube,  the  "Bourdon"  tube  of 
steam  gages,  etc.,  the  particular  property  of  which  is  its  tendency  to 
straighten  out  when  subjected  to  the  influence  of  an  internal  pressure.  In 
this  model  pressure  is  intermittently  supplied  by  the  successive  explosion  of 
cartridges  in  the  revolver  barrel — shown  in  the  U  of  the  tube — which  com- 
municates with  the  interior.  In  this  way  a  series  of  vigorous  flaps  can  be 
obtained,  with  flight  for  as  much  as  240  feet. 

described  in  Figure  25.  Not  the  least  curious 
feature  of  this  model  was  the  method  of  starting 
it  by  the  use  of  two  strings,  successively  cut  by 
a  candle  and  a  blowpipe  flame.* 


*  Described  in  Channte's  "Progress  in  Flying  Machines." 


122 


VEHICLES  OF  THE  AIR 


A  most  ingenious,  persistent,  unselfish,  and 
well-equipped  investigator  of  flying-machine  prob- 
lems is  Laurence  Hargrave,  of  Sidney,  Australia, 
who  is  known  the  world  over  as  the  inventor  of 
the  box  kite  (see  Figure  34). 

In  the  course  of  his  experiments  with  ornithop- 
ter  constructions — in  which  flapping  wings  were 


FIGURE  26. — Engine  and  Wing  Mechanism  of  Hargrave  Model  No.  18.  The 
boiler  of  thig  machine  was  of  the  water-tube  type,  constituted  of  21  feet  of 
%-inch  copper  tubing  with  an  internal  diameter  of  .18  inch.  The  tubing  was 
arranged  in  three  concentric  vertical  coils,  1.6  inches,  2.6  inches,  and  3.6 
inches  in  diameter,  inclosed  in  an  asbestos  jacket.  The  weight  was  37 
ounces,  but  Hargrave  asserted  that  it  could  be  lightened  to  8  ounces  without 
reducing  the  capacity  and  with  the  retention  of  ample  strength.  The  engine 
was  single-cylinder,  double-acting,  of  2  inches  bore  and  2.52  inches  stroke, 
and  with  piston  valves  .3  inch  in  diameter.  The  wings  were  flapped  directly, 
with  no  conversion  of  the  reciprocating  into  rotary  motion,  and  the  highest 
speed  attained  was  342  strokes  a  minute.  The  total  weight  of  engine,  boiler, 
and  21  ounces  of  water  and  alcohol,  enough  to  feed  the  boiler  and  burner  for 
four  minutes,  was  7  pounds.  The  Indicated  horsepower  was  .653,  with  a 
capacity  for  evaporating  14.7  cub'c  Inches  of  water,  with  4.13  cubic  Inches 
of  alcohol,  in  thirty  seconds.  This  figures  8.71  pounds  to  the  horsepower 
for  the  power  plant  with  tanks  empty,  or  5.93  pounds  to  the  horsepower  were 
the  expected  lightening  of  the  boiler  realized.  The  wings  were  36  inches 
long,  with  the  outer  22  Inches  covered  with  paper,  4  inches  wide  at  the  inner 
ends  and  9  inches  wide  at  the  tips — a  total  of  286  square  inches  for  the  two 
wings.  Thrusts  of  as  high  as  one  pound  were  obtained  and  machines  of  sim- 
ilar type  flew  distances  of  several  hundred  feet.  The  flapping  wings  were 
used  for  propulsion  alone,  sustention  being  had  from  the  large  aeroplane  sur- 
face to  the  rear. 

invariably  employed  for  propulsion,  not  susten- 
tion— Hargrave  built  eighteen  different  machines, 


HEAVIER-THAN-AIR  MACHINES         123 

commencing  1883  and  culminating  in  1893,  with 
the  machine  illustrated  and  described  in  Figure  26. 
Of  the  eighteen  machines,  which  were  built  on 
similar  lines  but  variously  propelled  by  clockwork, 
rubber  bands  in  torsion  and  tension,  compressed 
air,  and  steam,  several  were  built  with  single  and 
double  and  traction  and  thrust  screw  propellers, 
that  the  action  and  efficiencies  of  these  might  be 
compared  with  one  another  and  with  the  wings. 

A  remarkable  feature  of  many  of  the  Hargrave 
models  is  the  wonderful  lightness  of  the  small 
power  plants,  which  while  built  inexpensively, 
rather  crudely,  and  in  a  decidedly  tinkering  sort  of 
way,  have  never  been  surpassed  in  the  ratio  of 
power  to  weight  except  in  a  very  few  of  most 
modern  gasoline  engines. 

With  different  ones  of  these  models,  the  best 
of  which  weighed  from  about  four  to  eight  pounds, 
and  ranged  up  to  6  feet  in  length  and  width, 
recorded  flight  of  343  feet  was  definitely  accom- 
plished as  early  as  1891,  with  at  least  one  similar 
model  built  to  carry  within  its  weight  limit  enough 
fuel  to  fly  for  a  mile.  The  maximum  speeds 
attained  were  about  17  miles  an  hour. 

After  1893,  when  his  box  or  " cellular"  kite 
was  developed,  Hargrave  turned  his  attention  to 
the  development  of  this  type  of  sustaining  surface, 
which  has  come  to  be  regarded  as  the  direct  proto- 
type of  at  least  one  most  successful  modern  biplane 
— the  Voisin. 


124  VEHICLES  OF  THE  AIR 

TWO  CHIEF  CLASSES 

The  work  of  Hargrave  particularly  emphasizes 
the  fact  that  the  ornithopter  principle  is  capable 
of  application  to  either  of  two  wholly  different 
classes  of  machines — those  sustained  in  the  air 
solely  by  the  movement  of  the  wings,  and  others, 
usually  aeroplanes,  in  which  the  flapping  is  used 
simply  for  propulsion.  For  further  consideration 
of  ornithopter  propulsion  see  Page  25. 

RECENT  ORNITHOPTERS 

At  the  time  this  is  written  the  only  known  sec- 
cessful  machiness  of  the  ornithopter  type  are  the 
very  small  models  of  Jobert,  Penaud,  Pichancourt, 
Trouve,  and  Hargrave — the  latter  being  really 
areoplanes  with  ornithopter  propulsion.  Fur- 
thermore, no  materially  greater  success  seems  at 
all  probable,  for  the  reasons  explained  on  Page  25 
— reasons  that  are  further  upheld  by  the  invariable 
failure  and  unmechanical  construction  of  every 
ornithopter  of  man-carrying  size  that  has  so  far 
appeared.  A  characteristic  example  is  the  machine 
illustrated  in  Figure  27,  in  which  are  wing  struc- 
tures and  actuating  elements  are  nowhere  near 
strong  enough  to  withstand  the  rate  of  flapping 
necessary  to  effect  sustention.  Another  example 
was  the  Farcot  machine,  exhibited  in  Paris  in  Octo- 
ber, 1909. 

ANALOGIES  IN  NATURE 

That  the  flapping-wing  machine  has  not  met 
with  the  success  of  its  animal  prototypes  is  beyond 
any  question  due  to  the  invariable  superiority  of 


HEAVIER-THAN-AIR  MACHINES         125 

rotating  over  reciprocating  mechanisms  in  all 
mechanical  structures  man  has  the  means  and  the 
knowledge  to  devise,  and  in  which  the  one  most 
conspicuous  feature  is  the  frequent  use  of  the  wheel 
and  its  various  equivalents,  which  are  unknown  in 
nature  apparently  not  because  they  are  not  supe- 
rior but  because  they  are  not  available.  This  view, 
which  is  somewhat  amplified  on  Page  26,  gives 
ground  for  the  belief  that  as  man  does  learn  to 
fly  he  will  do  •  so  more  efficiently  though  not 
necessarily  as  safely  as  the  birds,  just  as  his  water 
craft  excel  the  inhabitants  of  the  deep  and  his  land 
vehicles  the  creatures  of  the  land  in  speed,  sus- 
tained travel,  and  loads  carried. 

HELICOPTERS 

Though  in  almost  the  same  status  as  the  ornith- 
opter,  in  so  far  as  any  measurable  success  that 
has  been  achieved  is  concerned,  engineers  are 
nevertheless  inclined  to  regard  with  some  measure 
of  respect  the  helicopter  principle,  which  in  many 
essentials  appears  to  be  quite  sound  engineering, 
and  which  is  vigorously  defended  by  men  like 
Edison,  Berliner,  Cornu,  Breguet,  and  others. 
Even  the  assertion  that,  no  matter  what  success 
may  be  attained  with  the  helicopter,  it  must  always 
prove  unsafe  upon  failure  of  the  power,  is  met 
by  plausible  and  well-backed  reasoning  to  the 
effect  that  the  propeller  areas  can  be  sufficient  to 
prevent  abrupt  descent,  causing  the  machine 
simply  to  act  as  a  parachute  in  case  the  power 


126  VEHICLES  OF  THE  AIR 

fails.  As  for  an  analogy  in  nature,  it  is  a  fact 
that  the  delicately-twisted  wing  of  the  ash  seed  by 
causing  fairly  rapid  revolution  definitely  retards 
the  fall.  The  forms  of  maple  and  sycamore  seeds, 
too,  produce  a  similar  effect,  though  these  are  less 
screw-propeller-like.  In  the  matter  of  sustention, 
while  it  is  true  that  nature  finds  the  helicopter 
principle  unavailable,  it  is  a  fact  that  in  the  cases  of 
humming  birds  and  many  insects  there  is  to  be 
found  the  closest  imaginable  approximation  to  this 
principle,  in  the  use  of  flat  blade-like  wings  that 
buzz  to  and  fro  with  rapidly  reversing  angles  of 
incidence  through  arcs  as  great  as  250°. 

It  has  been  frequently  sought  to  combine  the 
helicopter  principle  with  that  of  the  aeroplane,  as 
in  balanced  balloons  in  which  it  is  sought  to  cause 
the  vessel  to  ascend  or  descend  by  revolving  a 
propeller  in  a  horizontal  plane.  A  recent  com- 
bination of  a  helicopter  with  an  aeroplane  is  shown 
in  Figure  33. 

HISTOBY 

Leonardo  da  Vinci,  the  wonderful  Italian 
genius  of  the  middle  ages,  who  looms  so  large  in 
so  many  fields  of  endeavor,  did  not  overlook  the 
possibilities  of  the  helicopter  as  a  means  to  man 
flight,  for  in  one  of  his  note  books  there  is  a  sketch 
of  a  proposed  lifting  propeller  96  feet  in  diameter, 
to  be  built  of  iron  and  bamboo  framing,  covered 
with  starched  linen.  The  idea  was  evidently 
dropped  because  of  the  power  required,  but  it  is 
recorded  that  light  paper  propellers  were  experi- 


FIGURE  27. — Collomb  Ornithopter.  This  machine  is  of  the  direct,  orthogonal  flapping-wing 
type,  provided  with  valvular  flaps  at  a  a  a  a.  The  two  wings,  which  pivot  at  the  upper 
extremities  of  the  links  c  c  c  c,  are  reciprocated  by  the  vertical  reciprocation  of  the  arms  d  d. 


FIGURE  31. — Bertin  Helicopter. 


HEAVIER-IE  AN -AIR  MACHINES         127 


mented  with  and  made  to  ascend  for  very  brief 
periods. 

In  1784,  only  a  year  after  the  Montgolfiers'  first 
balloon  ascension,  Launoy  and  Bienvenu  jointly 
exhibited  before  the  French  Academy  of  Sciences 
the  little  helicopter  pictured  in  Figured  28.  This 
toy,  which  can  be  easily  made  from  a  couple  of 
corks,  a  few  feathers,  a  piece  of  thread,  and  a 
splint  of  bamboo,  is  an  excellent  flier,  continuing 
to  ascend  until  the  thread  is  completely  unwound. 
Of  the  totally  unsuccessful  or  merely  projected 
helicopters  there  has  been  a  great  number,  few  of 
which  merit  description  except  in  a  work  devoted 
to  the  historical  rather  than  to  the  practical  in 
aeronautics. 

The   next   advance   in   helicopters   after   the 

Launoy  and  Bienvenu  in- 
vention was  made  by  W. 
H.  Phillips,  who  uTl842 
made  a  2-pound  helicopter, 
driven  by  a  reaction  tur- 
bine similar  to  the  first  en- 
gine, attributed  to  Hero,  of 
Alexandria.  This  model  is 
stated  to  have  flown  across 
two  large  fields,  but  was 
badly  broken  in  landing. 

In  1870  Penaud  devised 
a  toy  helicopter,  driven 
by  a  rubber  band  and  exactly  similar  to  that  shown 
in  Figure  29,  except  that  in  place  of  the  large  sur- 
faces to  keep  the  whole  apparatus  from  turning 


28.— Toy 

propeller 


Helicopter, 
blades     are 


suitably  placed  feathers  and  the 
power  is  derived  from  the  bamboo 
splint  a,  which  in  straightening 
out  as  suggested  by  the  dotted 
lines  revolves  the  vertical  shaft. 


128 


VEHICLES  OF  THE  AIR 


FIGUKE  29. — Toy  Helicopter.  By 
turning  the  propeller  until  the  rub- 
ber band  a  is  tightly  twisted,  energy 
enough  is  stored  for  a  short  flight, 
the  large  wings  resisting  the  tendency 
of  the  whole  device  to  revolve  oppo- 
sitely to  the  propeller. 


a  duplicate  screw  was  provided  at  the  bottom,  as 
in  Figure  28.     Flights  of  nearly  half  a  minute 

were  obtained — much 
longer  than  had  been 
previously  obtained 
with  lifting  screws. 

The  helicopter  shown 
in  Figure  29  was  in- 
vented by  Dandrieux, 
and  has  been  extensively 
manufactured  in  France 
and  Japan  as  a  toy. 

Another  common 
toy,  said  to  have  devel- 
oped from  the  Penaud 
helicopter,  is  that  shown  in  Figure  30.  Wenham 
made  exhaustive  measurements  and  calculations 
with  these  toys,  and 
estimated  that  the 
best  of  them  will  lift 
33  pounds  per  horse- 
power —  well  within 
the  capacity  of  many 
modern  engines,  even 
of  large  size. 

Subsequent  to  this 
Edison,  Renard,  and 
Maxim  conducted  ex- 
haustive tests  of  pro- 
peller thrusts,  for  lift- 
ing as  well  as  for  propulsion,  but  their  work  proved 
only  of  scientific,  rather  than  of  practical  value. 


FIGURE  30. — Toy  Helicopter.  By  rap- 
idly pulling  the  string  the  propeller  i* 
revolved  at  such  speed  as  to  cause  it  to 
rise  off  the  spool  and  ascend  a  consid- 
erable distance  in  the  air. 


HEAVIER-THAN-AIR  MACHINES         129 

Also,  the  findings  of  these  early  investigators  have 
for  the  most  part  been  kept  secret,  leaving  the 
subject  still  much  in  need  of  investigation  and 
elucidation. 

EECENT  EXPERIMENTS 

Emil  Berliner,  the  famous  telephone  inventor, 
has  given  considerable  attention  to  the  develop- 
ment of  the  helicopter  principle,  and  according 
to  recent  accounts  had  tested  in  Washington,  D.  C., 
a  machine  expected  to  weigh,  with  operator,  only 
a  little  over  300  pounds.  This  machine  was  pro- 
vided with  a  36-horsepower  revolving-cylinder 
Adams-Farwell  motor,  weighing  100  pounds  and 
running  normally  at  1400  revolutions  a  minute, 
but  geared  to  drive  the  17-foot  propeller  at  150 
revolutions  a  minute.  At  this  speed  a  lift  of 
360  pounds  was  calculated,  but  it  is  not  known 
what  results  were  secured  in  the  actual  tests. 
Berliner  is  now  building  a  twin-screw  machine, 
expected  to  weigh  500  pounds  and  lift  720  pounds. 
This  machine  is  to  be  driven  by  a  55-horsepower 
Adams-Farwell  revolving-cyclinder  engine,  with 
five  5-inch  by  5-inch  plain  steel  cylinders,  and  a 
total  weight  of  only  175  pounds. 

An  ingenious  modern  helicopter,  seemingly  of 
fairly  sound  design  but  not  proved  successful  is 
that  illustrated  in  Figure  31. 

Another  interesting  new  helicopter  is  that  of 
Cornu,  which  is  illustrated  in  Figure  32.  In  tests 
this  has  proved  to  lift,  but  has  never  been  per- 
mitted to  rise  more  than  15  inches  from  the  ground, 
for  fear  of  accident. 


130  VEHICLES  OF  THE  AIR 

On  July  22,  1908,  the  Breguet  helicopter- 
aeroplane  is  said  to  have  flown  64  feet  at  a  maxi- 
mum height  of  15  feet. 

LATERAL  PROGRESSION 

After  the  problem  of  efficient,  reliable,  and  safe 
sustention  with  the  helicopter  is  solved,  there  will 
still  remain  the  problem  of  securing  controlled  lat- 
eral and  angular  movement.  Probably  the  com- 
monest as  well  as  the  most  promising  proposal 
contemplates  a  tilting  of  the  screw,  or  of  the 
machine — which  amounts  to  the  same  thing 
— so  that  there  will  be  a  combined  lateral  and  ver- 
tical thrust.  In  actual  tests  of  the  Beliner  heli- 
copter, it  is  said  to  have  been  established  that  with 
the  plane  of  rotation  inclined  15°  the  loss  in  lift 
was  less  than  3%,  while  the  hortizontal  element  of 
the  thrust  was  25%  of  the  lift. 

Another  common  plan  for  lateral  propulsion 
consists  in  the  use  of  supplementary  propellers  on 
a  horizontal  axis,  in  addition  to  the  lifting  screw 
on  a  vertical  axis.  Such  a  combination  appears 
in  the  machine  illustrated  in  Figure  33. 

The  Cornu  machine,  shown  in  Figure  32,  is 
intended  to  be  steered  by  rudders. 

It  is  a  point  in  favor  of  the  helicopter  that  the 
sustaining  effect  of  a  propeller  is  materially  greater 
when  it  is  given  movement  parallel  to  its  plane 
of  rotation  than  it  is  when  tested  without  change 
of  location.  This  effect  appears  to  be  due  to  the 
advantage  of  working  against  new  air  in  prefer- 
ence to  that  already  set  in  movement. 


EEAVIER-THAN-AIR  MACHINES         131 

ANALOGY  WITH  AEEOPLANE 

It  is  not  to  be  forgotten,  in  any  consideration 
of  the  practicability  or  the  prospects  of  the  heli- 
copter, that  its  propeller-blade  surfaces  are  essen- 
tially aeroplanes  caused  to  travel  in  circular  paths. 
This  would  seem  to  bring  their  action  within  the 
domain  of  practically  the  identical  laws  that  apply 
to  the  aeroplane,  and  might  be  taken  to  offer  simi- 
lar promise  of  future  success,  once  the  peculiarities 
of  the  particular  application  are  properly  worked 
out. 

AEROPLANES 

This  subject  is  too  important  to  treat  exhaust- 
ively here,  for  which  reason  Chapters  4  and  13 
have  been  entirely  given  over  to  descriptions,  and 
to  consideration  of  the  technical  details  involved 
in  the  construction  of  successful  modern  aero- 
planes, leaving  it  necessary  here  only  to  outline  the 
more  important  historical  facts  that  relate  to  the 
aeroplane. 

Just  as  the  ornithopter  developed  from  obser- 
vation of  the  more  difficult  flight  of  common  flap- 
ping wing  creatures,  so  the  aeroplane  has  devel- 
oped from  observation  of  the  magnificent  effort- 
less flight  of  the  less-common  soaring  birds. 

There  is  no  possible  doubt  but  what  the  aero- 
plane is  the  first  successful,  and  very  probably  des- 
tined to  continue  the  most  successful,  type  of  fly- 
ing machine.  Almost  everything  is  in  its  favor. 
In  its  best  forms,  for  example,  its  inherent  stabil- 
ity as  a  glider  may  constitute  an  almost  perfect 


132  VEHICLES  OF  TEE  AIR 

safeguard  against  the  possibility  of  accident  due  to 
motor  failure.  Moreover,  the  aeroplane  certainly 
will  prove  far  cheaper  to  build  and  to  operate  than 
any  conceivable  type  of  ornithopter,  and  probably 
cheaper  than  any  helicopter  that  will  begin  to 
afford  equivalent  speeds,  lifts,  or  efficiencies. 

AEROPLANE  HISTORY 

The  history  of  the  aeroplane  involves  the  devel- 
opment of  three  more  or  less  separate  conceptions 
— the  first,  the  use  of  gliding  surfaces  as  means  of 
riding  down  a  slant  of  air  from  a  greater  height 
to  a  lower;  the  second,  the  application  of  power- 
operated  propelling  elements  for  continuing  on  a 
horizontal  course  or  progressing  on  an  upward 
slant ;  and  the  third,  the  idea  of  indefinite  soaring 
without  power  by  the  utilization  of  obscure  and 
little  understood,  but  very  evident  principles,  that 
are  clearly  demonstrated  to  exist  in  the  flight  of 
soaring  birds — a  mode  of  flight  concerning  which 
there  has  been  much  speculation  and  controversy, 
and  the  performance  of  which  is  variously  attribr 
uted  to  the  phemomenon  of  rising  currents  in  the 
atmosphere,  to  the  presence  of  constantly  varying 
factors  in  the  horizontal  movement  of  winds,  and  to 
the  operation  of  laws  not  yet  generally  formulated 
or  recognized.  Probably  the  real  explanation  lies 
in  some  measure  of  sound  reasoning  that  is  to  be 
found  in  both  the  first  and  the  third  of  these 
explanations. 

Just  as  the  ornithopter.  is  a  logical-enough  out- 
growth from  observations  of  the  flapping  flight  of 


HEAVIER-THAN-AIR  MACHINES         133 

birds,  so  the  aeroplane  is  an  inevitable  deduction 
from  the  flight  of  soaring  birds.  And  so  absolute 
has  been  the  ignorance  and  misunderstanding  of 
the  phenomena  of  soaring  flight  that  even  today 
the  most  successful  aeroplanes  are  in  many  in- 
stances radically  incorrect  surfaces  made  to  fly  not 
so  much  by  sound  design  and  engineering  refine- 
ment as  by  being  inefficiently  dragged  through  the 
air  by  sheer  force  of  the  excessive  power  that  has 
become  available  in  modern  light-weight  engines. 
Of  the  many  investigators  of  aeroplane  prob- 
lems, it  is  a  safe  assertion  that  the  most  important, 
original,  and  successful  work  that  has  been  done 
is  fairly  to  be  ascribed  to  a  comparatively  small 
number  of  men — preeminent  among  whom  are 
Ader,  Bleriot,  Chanute,  Langley,  the  Lilienthals, 
Montgomery,  Penaud,  Pilcher,  Santos-Dumont, 
Wenham,  the  Wrights,  and  the  Voisins.  While 
this  list  may  not  at  all  fit  the  selections  or  opinions 
of  other  compilers  it  at  least  represents  a  serious 
and  unbiased  effort  justly  to  appraise  the  compara- 
tive value  of  the  many  different  contributions  to 
aeronautical  progress,  and  certainly  it  must  be  ad- 
mitted that  the  men  it  includes  are  in  any  case 
possessed  of  a  forever  unassailable  rank  in  this 
field  of  engineering.  As  for  the  many  important 
omissions,  these  are  in  no  sense  intended  to  dis- 
parage the  earnest  and  valuable  researches  of  a 
considerable  number  of  able  and  disinterested  stu- 
dents, who  in  more  than  one  instance  have  freely 
given  years  of  their  lives  and  large  sums  of  money 
to  the  always  thankless  task  of  contributing  to  the 


134  VEHICLES  OF  THE  AIR 

progress  of  the  race  in  advance  of  commercial  de- 
mand and  in  the  face  of  popular  skepticism.  But, 
in  the  case  of  each  of  these  omissions,  it  is  the 
writer's  belief  that  no  fair  and  unprejudiced  analy- 
sis can  fail  to  discover  either  such  lack  of  orig- 
inality or  of  success  as  must  properly  reduce  to  a 
secondary  status  the  particular  experiments  af- 
fected. 

CLEMENT  ADEB 

In  1872  this  inventor,  well  known  as  one  of  the 
European  pioneers  in  the  development  of  the  tele- 
phone, constructed  a  53-pound  ornithopter  appa- 
ratus in  the  form  of  a  bird  of  a  26-foot  wing  spread, 
intended  to  be  flown  by  the  strength  of  the  opera- 
tor's muscles.  Failure  naturally  resulting,  the 
project  was  dropped  and  it  was  not  until  1891  that 
Ader  began  his  aeroplane  experiments  with  the 
construction  of  a  bat-like  machine,  54  feet  across, 
weighing  1100  pounds,  and  drawn  through  the  air 
by  two  four-bladed  tractor  screws,  driven  by  a 
twenty  or  thirty  horsepower  steam  power  plant. 
Fully  $120,000  was  expended  in  the  experiments, 
and  the  result  was  the  first  flight  of  a  man-carrying 
power-propelled  aeroplane,  for  a  distance  of  only 
164  feet,  on  October  9,  1890.  Subsequently,  on 
October  14, 1897,  at  Satory,  France,  a  semicircular 
flight  of  nearly  1000  feet  was  accomplished  with  a 
machine  started  by  a  run  along  the  ground  on 
wheels.  In  both  of  these  trials  the  machines  were 
wrecked  because  of  deficient  equilibrium. 


HEAVIER-THAN-AIR  MACHINES          135 

LOUIS  BLERIOT 

One  of  the  earliest  among  the  successful  aero- 
plane builders  of  the  world  is  Louis  Bleriot,  who 
has  long  been  noted  as  one  of  the  foremost  auto- 
mobile-lamp manufacturers  in  Europe,  and  whose 
experiments  commenced  like  those  of  so  many 
others  with  a  flapping-wing  machine,  built  in  1901. 
Following  the  failure  of  this,  nothing  more  was 
done  until  during  1905,  when  some  interesting  ex- 
periments were  made  with  a  towed  biplane  glider — 
Bleriot  II — mounted  on  hydroplanes.  The  Bleriot 
III  was  a  double  biplane  of  box  kite  form,  but  with 
semicircular  instead  of  vertical  ends.  It  was  pro- 
vided with  a  motor  but  no  success  resulted  from 
attempts  to  make  it  rise  from  the  Seine,  on  the  sur- 
face of  which  it  was  floated  like  its  predecessor. 
Bleriot  IV  was  Bleriot  III  modified  by  removal 
of  the  semicircular  ends  from  the  front  cell,  but 
not  until  experiments  on  land  were  substituted  for 
those  over  water  and  a  double  monoplane  for  the 
biplane  was  the  first  real  flight  accomplished — in 
July,  1907.  After  this  the  monoplane  principle 
was  rapidly  developed,  with  numerous  successes  in 
1908  and  more  in  1909,  culminating  in  the  wonder- 
ful cross-country  flights  in  the  spring  and  summer 
of  the  latter  year,  and,  finally,  in  the  memorable 
crossing  of  the  English  Channel  in  one  of  the 
smallest,  speediest,  lowest-powered,  and  cheapest 
aeroplanes  yet  built. 


136  VEHICLES  OF  THE  AIR 

OCTAVE  CHANUTE 

Commencing  in  1896  with  experiments  with  a 
Lilienthal  glider,  this  well-known  engineer,  noted 
as  a  bridge  and  railway  builder,  progressed  to  the 
development  of  machines  of  his  own  design,  de- 
vised to  eliminate  the  dangers  and  improve  upon 
the  results  encountered  in  the  use  of  the  Lilien- 
thal apparatus.  The  trials  made  at  Dune  Park, 
Indiana,  by  Chanute  and  his  assistants,  A.  M.  Her- 
ring and  William  Avery,  quickly  led  to  the  use  of 
multi-surface  machines,  of  as  many  as  four  or  five 
superimposed  decks.  With  these — particularly 
with  the  biplane  (see  Figure  237)  that  the  Wrights 
subsequently  developed,  with  Chanute 's  constant 
assistance  and  advice  and  frequent  presence  from 
the  very  first  experiments  until  flying  was  actu- 
ally accomplished,  and  with  a  similar  triplane 
— over  2000  glides,  of  a  maximum  length  of  360 
feet,  were  safely  accomplished.  A  feature  of  the 
final  Chanute  machines  was  the  use  of  a  modified 
form  of  swinging  wing  tip,  patented  by  Chanute  in 
the  form  illustrated  in  Figure  261. 

SAMUEL  PIEEPONT  LANGLEY 

One  of  the  most  painstaking,  well-equipped,  and 
successful  students  of  aerodynamic  problems  was 
Professor  Langley,  of  the  Smithsonian  Institution, 
who,  after  much  preliminary  investigation  of  the 
action  of  supporting  surfaces  constructed  a  number 
of  double-monoplane  models,  of  the  type  illustrated 
in  Figure  70,  which  repeatedly  flew  for  distances 


HEAVIER-THAN-AIR  MACHINES        137 

of  half  a  mile  and  more  over  the  Potomac  River. 
The  first  of  these  flights  was  on  May  6,  1896,  and 
is  described  in  Nature — issue  of  May  28,  1896 — by 
Alexander  Graham  Bell,  who  witnessed  it.  After 
exhaustive  and  uniformly  successful  experiments 
with  models,  an  appropriation  of  $50,000  from  the 
United  States  War  Department  was  expended  in 
the  construction  of  a  similar  machine  of  man-carry- 
ing size,  weighing  830  pounds  and  propelled  by  a 
52-horsepower  gasoline  engine.  This  machine  was 
twice  tried,  on  October  7  and  December  8, 1903,  but 
both  times  was  plunged  in  the  Potomac  by  defects 
in  the  launching  apparatus.  It  is  a  general  belief 
that  in  calm  weather  this  machine  is  capable  of 
fairly  stable  flight,  but  no  tests  have  been  made  of 
it  since  the  inconclusive  trials  referred  to. 

OTTO  AND  GUSTAV  LILIENTHAL 

Probably  no  other  worker  in  the  history  of  aero- 
nautical science  is  entitled  to  a  higher  place  than 
Otto  Lilienthal,  whose  early  and  thorough  investi- 
gation of  the  subject,  in  association  with  his 
brother  Gustav,  have  formed  the  groundwork  for 
a  large  proportion  of  subsequent  successful  exper- 
iments, and  whose  martyrdom  to  the  advancement 
of  flight  is  a  loss  that  never  can  be  estimated. 
Lilienthal 's  investigations,  which  commenced  in 
1871  and  progressed  to  actual  gliding  experiments 
in  1891,  were  of  a  thoroughness  that  few  have  ex- 
ceeded, many  of  his  conclusions  being  still  regarded 
as  part  of  the  gospel  of  most  students.  All  told  he 
performed  over  2000  glides,  of  a  maximum  length 


138  VEHICLES  OF  THE  AIR 

of  1000  feet  and  at  a  maximum  speed  of  twenty- 
two  miles  an  hour.  Though  originally  a  firm  be- 
liever in  the  monoplane  (see  Figures  230,  231,  and 
263),  and  in  the  ultimate  attainment  of  soaring 
flight,  in  1896  he  built  a  2J-horsepower  motor, 
weighing  88  pounds,  and  it  was  in  testing  the  bi- 
plane sketched  in  Figure  232,  to  which  he  proposed 
the  application  of  flapping  propulsion  by  the  use  of 
his  motor,  that  he  met  his  death  by  a  fall  from  a 
height  of  50  feet,  on  August  10,  1896. 

JOHN  J.   MONTGOMERY 

The  history  of  engineering  abounds  in  examples 
of  the  struggling  inventor  who,  having  realized  the 
labor  of  his  brain  in  the  form  of  a  concrete  mechan- 
ism of  more  or  less  incalculable  value,  is  thereafter 
accorded  neither  deserved  recognition  nor  any  ade- 
quate share  in  the  material  returns  from  his  work, 
which  is  commonly  seized  and  exploited  by  more 
assertive  egotisms  and  sturdier  greeds.* 

On  April  29, 1905,  in  California,  there  was  pub- 
licly performed  a  feat  which  no  competent  and  un- 
prejudiced person  who  investigates  its  details  can 
fail  to  characterize  as  the  greatest  single  advance 
in  the  history  of  aerial  navigation.  For  on  this  day 

*  It  is  a  fact  perhaps  worthy  of  remark  that  much  in  the  spirit  and 
methods  of  the  times  make  such  a  condition  perfectly  to  be  expected. 
A  large  proportion  of  the  lay  press  and  the  general  public,  the  one 
catering  to  and  deriving  its  support  from  the  other,  possess  neither  the 
deliberate  outlook  nor  the  special  knowledge  necessary  to  just  apprecia- 
tion and  appraisals  of  technical  merits  nnd  values,  while  the  average 
institutions  of  higher  learning,  from  which  the  inculcation  of  better- 
balanced  opinions  might  be  reasonably  expected,  are  too  commonly 
devoted  to  following  instead  of  leading  scientific  progress,  and  to  occupy- 
ing the  developing  mind  with  mnemonic  feats  of  remembering  solved 
problems  instead  of  with  the  exercise  of  reasoning  out  unsolved  ones. 


HEAVIER-THAN-AIR  MACHINES          139 

there  ascended  from  the  college  grounds  at  Santa 
Clara,  in  the  presence  of  thousands  of  spectators, 
an  ordinary  heated  air  balloon — to  which  was  at- 
tached, not  a  parachute,  but  a  45-pound  glider  de- 
signed by  Professor  Montgomery  and  mounted  by 
an  intrepid  parachute  jumper,  Daniel  Maloney 
(see  Figures  225,  226,  227,  and  260). 

At  a  height  of  about  4000  feet  the  aeroplane  was 
cut  loose  from  the  balloon  and  commenced  to  glide, 
under  the  most  absolute  control  imaginable,  to  the 
ground.  In  the  course  of  the  descent  the  most 
extraordinary  and  complex  maneuvers  were  ac- 
complished— spiral  and  circling  turns  being  exe- 
cuted with  an  ease  and  grace  almost  beyond  de- 
scription, level  travel  accomplished  with  the  wind 
and  against  it,  figure-eight  evolutions  performed 
without  difficulty,  and  hair-raising  dives  were  ter- 
minated by  abrupt  checking  of  the  movement  by 
changing  the  angles  of  the  wing  surfaces.  At  times 
the  speed,  as  estimated  by  eye  witnesses,  was 
over  sixty-eight  miles  an  hour,  and  yet  after  a 
flight  of  approximately  eight  miles  in  twenty  min- 
utes the  machine  was  brought  to  rest  upon  a  previ- 
ously designated  spot,  three-quarters  of  a  mile 
from  where  the  balloon  had  been  released,  so  lightly 
that  the  aviator  was  not  even  jarred,  despite  the 
fact  that  he  was  compelled  to  land  on  his  feet,  not 
on  a  special  alighting  £ear. 

All  of  the  facts  of  this  wonderful  flight  are  well 
attested.  Newspaper  men  who  were  present  could 
not  find  terms  extravagant  enough  adequately  to 
praise  what  they  witnessed.  The  correspondent  of 


140  VEHICLES  OF  THE  AIR 

the  Scientific  American,  in  the  issue  of  that  peri- 
odical published  on  May  20,  1905,  declared  that 
"An  aeroplane  has  been  constructed  that  in  all 
circumstances  will  retain  its  equilibrium  and  is  sub- 
ject in  its  gliding  flight  to  the  control  and  guidance 
of  an  operator."  Octave  Chanute  characterized 
the  flight  as  "the  most  daring  feat  ever  attempted", 
and  Alexander  Graham  Bell  had  no  hesitation  in 
asserting  that  "all  subsequent  attempts  in  aviation 
must  begin  with  the  Montgomery  machine."  * 

While  it  is  difficult  for  a  trained  engineer,  for 
the  first  time  made  acquainted  with  Montgomery's 
work,  to  prevent  being  overwhelmed  by  its  extent 


*  It  is  a  fact  of  quite  unescapable  significance  that  recent  activity 
and  present  successes  in  aeronautics  do  date  most  definitely  from  the 
public  flights  of  the  Montgomery  machine  in  1905. 

On  page  48  of  the  June  issue  of  Motor  of  that  year — in  which  maga- 
zine the  writer  had  been  for  some  time  giving  space  to  a  column  on 
aeronautics — an  account  of  the  Montgomery  flights  and  an  illustrated 
description  of  the  Montgomery  machine  was  published.  Prior  to  this 
publication,  and  the  accounts  in  the  Scientific  American  already  referred 
to,  all  attempts  at  flight,  without  a  solitary  exception  that  is  authenti- 
cated, had  been  marked  by  ever-present  uncertainty  as  to  equilibrium, 
constant  hazard  to  the  operator,  and  frequent  accidents — ranging  from 
minor  mishaps  to  fearful  fatalities.  The  longest  flights  with  man-carry- 
ing machines  that  are  definitely  substantiated  before  this  time  were  the 
maximums  of  1000  feet  by  Lilienthal  and  Ader,  the  852  feet  by  the 
Wrights  in  1903,  and  the  1377-foot  flight  by  the  Wrights  in  1904,  wit- 
nessed by  Octave  Chanute.  All  of  these  ended  in  damage  to  the 
apparatus.  Subsequent  to  publication  and  circulation  of  these  accounts 
there  promptly  followed  the  experiments  with  motor-propelled  machines 
by  Ferber  in  France  during  1905;  the  fairly  successful  glides  of  Arch- 
deacon, and  of  Bleriot  and  the  Voisins,  over  the  Seine  in  June  and 
July,  1905;  the  remarkable  sustained  flights  of  the  Wright  brothers 
over  Huffman  Prairie,  Ohio,  between  September  26  and  October  5,  1905. 
and  the  flights  of  Santos-Dumont,  at  Bagatelle,  France,  in  August  and 
September,  1906. 

From  the  foregoing  it  seems  perfectly  fair  to  state  that  it  was  Mont- 
gomery's successes  that  gave  definite  and  recorded  beginning  to  the 
now  fast  advancing  period  of  man's  mastery  over  the  most  elusive 
medium  in  which  he  aspires  to  travel — mastery  absolutely  comparable 
to  that  of  the  bird,  fruitlessly  envied  and  copied,  and  copied  and  envied, 
by  earth-bound  man  from  the  fables  of  antiquity  until  March  and  April, 
1905. 


FIGURE  o2. — Cornu  Helicopter.  This  curious-appearing  contrivance  is  the  creation  of 
a  prominent  European  engineer  who  has  given  years  of  study  to  this  problem  The  two 
lifting  propellers  at  aa  are  mounted  on  bicycle-like  wheels  and  are  belt-driven  'in  oDDOsite 
directions  from  a  vertical  shaft.  The  flat  surfaces  66  are  for  lateral  control  and  stJerin-P 


FIGURE  33. — Bertin  Helicopter  Aeroplane. 


of  a  gull's 
" 


,  with  no  control  but  the  vertical  movement  of  the  tail      With  it  one  600-foot 
r*her  ariousl,   and  it   was  broken   in   an  attempt  to  repeat  the 

wye0S  5  ^£5^^  ^S^&S 


HEAVIER-THAN-A1R  MACHINES          141 

and  importance,  it  is  a  singular  though  not  inex- 
plicable fact  that  the  general  public  has  in  no 
measurable  degree  appreciated  what  he  has  accom- 
plished. Even  eye  witnesses  of  the  California 
flights  as  a  rule  seemed  to  imagine  that  something 
akin  to  a  parachute  jump  was  in  progress,  few 
realizing  that  the  one  great  problem  of  aerial  navi- 
gation from  the  beginning  had  been  that  of  con- 
trolled flight  and  maintained  equilibrium,  which 
here,  for  the  first  time  in  history,  it  was  their  privi- 
lege to  witness.* 

Of  even  greater  importance  than  his  experi- 
mental demonstrations  have  been  Professor  Mont- 
gomery's profound  researches  in  aerodynamics. f 
The  son  of  a  former  assistant  attorney-general  of 
the  United  States,  he  was  graduated  in  1879  from 
St.  Ignatius  College,^  in  San  Francisco,  with  abun- 
dant equipment  and  opportunities  for  investiga- 
tion of  his  favorite  subject,  to  which  he  has  devoted 

*  It  has  been  long  recognized  by  all  authorities  on  the  subject 
that  the  problem  of  propulsion  is  a  comparatively  minor  matter,  espe- 
cially now  that  high-power  and  light-weight  motors  have  been  made 
widely  available  by  the  development  of  the  automobile.  Lilienthal, 
D'Esterno,  and  Mouillard  all  have  expressed  the  conviction  that  indefi- 
nite soaring  flight  is  as  positively  possible  as  it  is  certain  that  birds 
perform  it;  Langley  wrote  his  paper  on  "The  Internal  Work  of  the 
Wind"  in  an  effort  to  explain  this  phenomenon;  Chanute,  in  his  essay 
on  "Soaring  Flight,"  stoutly  contends  that  we  are  on  the  verge  of  its 
accomplishment;  and  Wilbur  Wright  is  authority  for  the  statement  that 
"there  is  another  way  of  flying  which  requires  no  artificial  motor"  and 
which  "is  as  well  able  to  support  a  flying  machine  as  a  bird" — while 
even  in  the  Wright  patent  specifications  there  is  contemplated  flight 
"either  by  the  application  of  mechanical  power  or  by  the  utilization  of 
the  force  of  gravity. ' ' 

t  For  details  of  Montgomery 's  investigations  and  conclusions  see 
Chapter  4. 

t  Classmates  of  Professor  Montgomery  were  James  D.  Phelan, 
mayor  of  San  Francisco,  1896-1902,  and  Rev.  B.  H.  Bell,  well  known 
for  his  researches  in  wireless  telegraphy. 


142  VEHICLES  OF  THE  AIR 

the  larger  portion  of  his  life.  First  attracted  to 
aeronautical  problems  as  a  boy  in  1877,  it  was  not 
until  1883  that  Montgomery  built  his  first  machine, 
a  flapping- wing  contrivance  of  such  merits  that  one 
experiment  was  enough  to  convince  its  designer 
that  success  was  not  to  be  found  in  this  direction. 
From  this  beginning  dated  a  period  of  consist- 
ent experimenting,  which  for  priority,  originality, 
and  quality  of  its  practical  results  and  theoretical 
conclusions  has  not  been  approached  by  any  subse- 
quent investigator.  During  1884-85  three  gliders  * 
were  built,  from  the  first  of  which  a  glide  of  600 
feet  f  was  obtained  and  the  lifting  value  of  curved 
surfaces  (copied  from  the  sea-gull's  wings)  demon- 
strated; from  the  second  of  which  the  futility  of 
flat  surfaces  was  proved,  but  in  which  diagonally- 
hinged  rear  wing  portions  were  used  (practically 
analogous  to  the  Farman  device  that  the  Wrights 
are  seeking  to  enjoin  at  the  present  time)J;  and 

in  the  third  of  which  the  lateral  equilibrium  was 
maintained  by  pivoted  wings.  If 

Besides  the  flight  at  Santa  Clara,  many  others 
were  made,  some  of  them  presenting  most  remark- 


*  These  gliders  are  described  in  Chanute  's  i '  Progress  in  Flying 
Machines."  See  also  Figure  35. 

t  It  is  to  be  noted  that  this  glide,  which  was  performed  eight  or  nine 
years  before  Lilienthal's  experiments,  ranks  well  in  distance  with  them 
and  with  the  best  subsequent  glides  of  Pilcher,  Chanute,  the  Wrights, 
and  others  referred  to  in  the  tabular  history  of  flights  which  commences 
on  page  476. 


t  This  construction,  which  is  illustrated  in  Figure  35,  is  described  in 
Chanute 's  "Progress  in  Flying  Machines,"  on  page  249. 

If  This  arrangement  is  one  that  has  been  used  with  success  in  some 
of  the  latest  Antoinette  machines. 


HEAVIER-THAN-AIR  MACHINES         143 

able  features  and  one  terminating  in  a  fatal  acci- 
dent. The  full  details  of  these  are  deemed  of  suffi- 
cient importance  to  warrant  reproduction  in  its  en- 
tirety of  an  article  originally  published  in  The 
Aeroplane,  in  1905,  and  republished  in  January, 
1909,  in  Aeronautics.  This  article  follows  without 
alteration  except  to  correct  typography,  etc. : 

"When  I  commenced  practical  demonstration  in 
my  work  with  aeroplanes  I  had  before  me  three 
points;  First,  equilibrium;  second,  complete  control; 
and  third,  long  continued  or  soaring  flight.  In  start- 
ing I  constructed  and  tested  three  sets  of  models,  each 
in  advance  of  the  other  in  regard  to  the  continuance 
of  their  soaring  powers,  but  all  equally  perfect  as  to 
equilibrium  and  control.  These  models  were  tested  by 
dropping  them  from  a  cable  stretched  between  two 
mountain  tops,  with  various  loads,  adjustments  and 
positions.  And  it  made  no  difference  whether  the 
models  were  dropped  upside  down  or  any  other  con- 
ceivable position,  they  always  found  their  equilibrium 
immediately  and  glided  safely  to  earth. 

"Then  I  constructed  a  large  machine  patterned 
after  the  first  model,  and  with  the  assistance  of  three 
cowboy  friends  personally  made  a  number  of  flights 
in  the  steep  mountains  near  San  Juan  (a  hundred 
miles  distant).  In  making  these  flights  I  simply  took 
the  aeroplane  and  made  a  running  jump.  These  tests 
were  discontinued  after  I  put  my  foot  in  a  squirrel 
hole  in  landing  and  hurt  my  leg. 

"The  following  year  I  commenced  the  work  on  a 
larger  scale,  by  engaging  aeronauts  to  ride  my  aero- 
plane dropped  from  balloons.  During  this  work  I 
used  five  hot-air  balloons  and  one  gas  balloon,  five  or 
six  aeroplanes,  three  riders — Maloney,  Wilkie  and  De- 


144  VEHICLES  OF  THE  AIR 

folco — and  had  sixteen  applicants  on  my  list  and  had 
a  training  station  to  prepare  any  when  I  needed  them. 

"Exhibitions  were  given  in  Santa  Cruz,  San  Jose, 
Santa  Clara,  Oakland,  and  Sacramento.  The  flights 
that  were  made,  instead  of  being  haphazard  affairs, 
were  in  the  order  of  safety  and  development.  In  the 
first  flight  of  an  aeronaut  the  aeroplane  was  so  ar- 
ranged that  the  rider  had  little  liberty  of  action,  con- 
sequently he  could  make  only  a  limited  flight.  In 
some  of  the  first  flights,  the  aeroplane  did  little  more 
than  settle  in  the  air.  But  as  the  rider  gained  experi- 
ence in  each  successive  flight  I  changed  the  adjust- 
ments, giving  him  more  liberty  of  action,  so  he  could 
obtain  longer  flights  and  more  varied  movements  in 
the  flights.  But  in  none  of  the  flights  did  I  have  the 
adjustments  so  that  the  riders  had  full  liberty,  as  I 
did  not  consider  that  they  had  the  requisite  knowl- 
edge and  experience  necessary  for  their  safety;  and 
hence,  none  of  my  aeroplanes  were  launched  so  ar- 
ranged that  the  rider  could  make  adjustments  neces- 
sary for  a  full  flight. 

"This  line  of  action  caused  a  good  deal  of  trouble 
with  aeronauts  or  riders  who  had  unbounded  confi- 
dence and  wanted  to  make  long  flights  after  the  first 
few  trials,  but  I  found  it  necessary  as  they  seemed 
slow  in  comprehending  the  important  elements  and 
were  too  willing  to  take  risks.  To  give  them  the  full 
knowledge  in  these  matters  I  was  formulating  plans 
for  a  large  starting  station  on  the  Mount  Hamilton 
Kange  from  which  I  could  launch  an  aeroplane  capable 
of  carrying  two,  one  of  my  aeronauts  and  myself, 
so  I  could  teach  him  by  demonstration.  But  the  dis- 
asters consequent  on  the  great  earthquake,  completely 
stopped  all  my  work  on  these  lines.*  The  flights  that 


*  Since  the  foregoing  was  written  arrangements  have  been  made  and 
capital  interested  for  the  resumption  of  the  Montgomery  experiments. 


HEAVIER-THAN-AIR  MACHINES         145 

were  given  were  only  the  first  of  the  series  with  aero- 
planes patterned  after  the  first  model.  There  were  no 
aeroplanes  constructed  according  to  the  two  other  mod- 
els, as  I  had  not  given  the  full  demonstration  of  the 
workings  of  the  first,  though  some  remarkable  and 
startling  work  was  done.  On  one  accasion,  Maloney  in 
trying  to  make  a  very  snort  turn  during  rapid  flight 
pressed  very  hard  on  the  stirrup  which  gives  a  screw 
shape  to  the  wings  and  made  a  side  somersault.  The 
course  of  the  machine  was  very  much  like  one  turn 
of  a  corkscrew.  After  this  movement,  the  machine 
continued  on  its  regular  course.  And  afterwards  Wil- 
kie,  not  to  be  outdone  by  Maloney,  told  his  friends  he 
would  do  the  same,  and  in  a  subsequent  flight,  made  two 
side  somersaults,  one  in  one  direction  and  the  other  in 
an  opposite*  then  made  a  deep  dive  and  a  long  glide 
and,  when  about  three  hundred  feet  in  the  air,  brought 
the  aeroplane  to  a  sudden  stop  and  settled  to  the  earth. 
After  these  antics,  I  decreased  the  extent  of  the  pos- 
sible change  in  the  form  of  wing  surface  so  as  to  allow 
only  straight  sailing  or  only  long  curves  in  turning. 

"During  my  work  I  had  a  few  carping  critics  that 
I  silenced  by  this  standing  offer:  If  they  would  de- 
posit a  thousand  dollars  I  would  cover  it  on  this  prop- 
osition. I  would  fasten  a  150-pound  sack  of  sand  in 
the  rider's  seat,  make  the  necessary  adjustments,  and 
send  up  an  aeroplane  upside  down  with  a  balloon,  the 
aeroplane  to  be  liberated  by  a  time  fuse.  If  the  aero- 
plane did  not  immediately  right  itself,  make  a  flight, 
and  come  safely  to  the  ground,  the  money  was  theirs. 

"Now  a  word  in  regard  to  the  fatal  accident.f 
The  circumstances  are  these :  The  ascension  was  given 
to  entertain  a  military  company  in  which  were  many 


*  These  performances  were  witnessed  by  thousands  of  people.    The 
italics  are  ours. — [Eo.] 


t  On  July  18,  1905. 


146  VEHICLES  OF  THE  AIR 

of  Maloney 's  friends,  and  he  had  told  them  he  would 
give  the  most  sensational  flight  they  ever  heard  of. 
As  the  balloon  was  rising  with  the  aeroplane,  a  guy 
rope  dropping  switched  around  the  right  wing  and 
broke  the  tower  that  braced  the  two  rear  wings  and 
which  also  gave  control  over  the  tail.  We  shouted  to 
Maloney  that  the  machine  was  broken  but  he  prob- 
ably did  not  hear  us,  as  he  was  at  the  same  time  say- 
ing *  Hurrah  for  Montgomery's  airship',  and  as  the 
break  was  behind  him,  he  may  not  have  detected  it. 
Now  did  he  know  of  the  breakage  or  not,  and  if  he 
knew  of  it  did  he  take  a  risk  so  as  not  to  disappoint 
his  friends?  At  all  events,  when  the  machine  started 
on  its  flight  the  rear  wings  commenced  to  flap  (thus 
indicating  they  were  loose),  the  machine  turned  on 
its  back,  and  settled  a  little  faster  than  a  parachute. 
When  we  reached  Maloney  he  was  unconscious  and 
lived  only  thirty  minutes.  The  only  mark  of  any  kind 
on  him  was  a  scratch  from  a  wire  on  the  side  of  his 
neck.  The  six  attending  physicians  were  puzzled  at 
the  cause  of  his  death.  This  is  remarkable  for  a  verti- 
cal descent  of  over  2,000  feet." 

In  view  of  the  extensive  appropriation  and 
utilization  by  others  of  ideas  originated  by  him,  it 
must  be  a  source  of  considerable  satisfaction  to 
Professor  Montgomery  that  lie  holds  a  United 
States  patent  (see  Figure  260)  broadly  covering 
the  combination  of  "wing  warping"  with  curved 
surfaces* — the  only  sort  that  have  ever  flown. 

*  In  the  opinion  of  several  prominent  patent  attorneys,  there  is  no 
conflict  between  this  patent  and  the  earlier  one  issued  to  the  Wright 
brothers,  for  the  combination  of  "normally-flat  aeroplanes "  (see  Page 
455)  with  a  type  of  "wing  warping"  substantially  proposed  by  Le  Bris, 
D  'Esterno,  and  Mouillard,  and  tested,  if  at  all,  in  devices  that  have  been 
proved  inoperative.  But  in  all  of  the  Wright  machines  that  have  flown, 
and  in  most  other  successful  modern  machines,  there  appears  the  com- 
bination of  curved  surfaces  with  "wing  warping" — a  direct  infringe- 
ment of  the  Montgomery  patent. 


HEAVIER-THAN-A1R  MACHINES         147 

A.  PENAUD 

An  uncommonly  ingenious  inventor  of  aero- 
nautical devices  was  A.  Penaud,  who  began  before 
he  was  twenty  by  devising  the  toy  helicopter  re- 
ferred to  on  Page  127,  and  subsequently  made  the 
successful  toy  ornithopter  mentioned  on  Page  120. 
But  his  most  important  contribution  to  the  art  was 
a  half-ounce  model  aeroplane,  18  inches  wide  and 
20  inches  long,  closely  resembling  the  modern 
Bleriot  monoplanes  and  embodying  a  remarkable 
system  of  automatic  longitudinal  stability.  Pro- 
pelled by  twisted  rubber  bands,  this  model  made 
both  straight  and  circular  flights  up  to  a  maximum 
length  of  131  feet,  at  a  speed  of  over  8  miles  an 
hour.  Subsequently  Penaud  was  associated  with 
a  mechanician  named  Gauchot  in  a  plan  to  build 
a  monoplane  large  enough  to  carry  two  men.  This 
machine  was  to  have  weighed  2640  pounds  and  have 
a  sustaining  area  of  634  square  feet.  It  was  esti- 
mated that  with  20  or  30  horsepower  applied 
through  twin  tractor  screws  flight  could  be  accom- 
plished with  an  angle  of  incidence  of  2°,  at  a  speed 
of  60  miles  an  hour.  It  was  planned  to  experiment 
over  water  to  reduce  the  danger,  but,  a  motor  of 
the  necessary  lightness  not  being  found,  and  the 
inventor  being  tormented  by  misrepresentation  and 
an  incurable  hip  disease,  from  which  he  died  in 
October,  1880,  before  he  had  reached  his  thirtieth 
year,  nothing  came  of  a  project  that  possessed  at 
least  the  merit  of  being  planned  by  one  of  the  most 
able  men  who  ever  gave  his  attention  to  the  subject. 


148  VEHICLES  OF  THE  AIR 

PERCY  S.  PILCHEB 

Another  who  began  experiments  in  his  early 
youth  was  the  English  engineer  Pilcher,  whose 
interest  in  aeronautics  dated  from  1882,  when  he 
was  aged  15,  and  who  in  1892  commenced  the  con- 
struction of  his  first  glider,  closely  similar  to  those 
of  Lilienthal.  In  all  he  built  five  machines,  the 
first  of  which  had  such  pronouncedly  dihedral 
wings  that  it  promptly  proved  the  futility  of  seek- 
ing balance  by  a  low  placing  of  the  weight.  His 
final  and  most  successful  type,  the  "Hawk"  (see 
Figures  233  and  234),  was  provided  with  small 
bicycle  wheels,  had  lightly-curved  wing  surfaces, 
and  was  planned  to  sustain  a  total  weight  of  about 
250  pounds — including  a  2-horsepower  oil  engine — 
on  an  area  of  188  square  feet.  With  this  machine 
he  made  one  glide  of  800  feet  across  a  valley,  towed 
kitewise  at  11  miles  an  hour  by  a  cord  drawn  by 
running  boys,  with  a  five-fold  multiplying  gear 
having  a  tractive  effort  that  at  the  machine  meas- 
ured 30  pounds.  Drawings  for  the  necessary  engine 
were  made  and  study  of  the  problem  of  equilibrium 
continued  until  a  headlong  plunge  from  a  height  of 
not  over  40  feet,  caused  by  the  snapping  of  a  rudder 
guy,  resulted  in  Pilcher 's  death  on  October  1, 1899. 

ALBERTO  SANTOS-DUMONT 

To  Santos-Dumont,  besides  much  activity  in  the 
development  of  the  dirigible  balloon  (see  Page  82), 
is  due  the  credit  for  the  first  public  and  successful 
flight  in  a  power-driven  areoplane  in  Europe,  on 
August  22,  1906.  Following  this  he  has  been  a 


HEAVIER-THAN-AIR  MACHINES         149 

most  daring  and  indefatigable  worker,  fortunate 
in  the  possession  of  both  considerable  ability  and 
abundant  means.  The  result  up  to  the  present  time 
has  been  the  evolution  of  one  of  the  lightest  and 
most  successful  monoplanes  in  existence  (see  Fig- 
ure 221),  which  with  characteristic  unselfishness  its 
designer  has  placed  on  the  market  at  cost,  and  re- 
frained from  monopolizing  it  by  patents. 

F.  H.  WENHAM 

Mr.  F.  H.  Wenham,  who  died  so  recently  as 
August  11, 1908,  was  unquestionably  the  originator 
of  the  biplane  and  other  superimposed  multisur- 
f ace  constructions,  which  were  subsequently  devel- 
oped by  Hargrave  into  the  box  kite,  and  which  are 
so  conspicuous  a  feature  of  many  modern  aeroplane 
designs.  This  construction  he  patented  in  England 
in  1866,  in  which  year  he  also  presented  the  idea  in 
a  paper  read  at  the  first  meeting  of  the  Aeronaut- 
ical Society  of  Great  Britain.*  Despite  the  merits 
of  the  idea,  and  its  subsequent  successful  utilization 
by  many  inventors,  no  practical  application  of  the 
construction  ever  was  made  by  its  originator. 

WILBUR  AND  OEVILLE  WRIGHT 

Commencing  in  1900,  Wilbur  and  Orville 
Wright,  two  bicycle  repairmen  of  Dayton,  Ohio, 

*  In  this  paper,  which  has  become  a  classic  on  the  subject,  the  most 
interesting  portion  is  as  follows:  "Having  remarked  how  thin  a 
stratum  is  displaced  beneath  the  wings  of  a  bird  in  rapid  flight,  it  fol- 
lows that,  in  order  to  obtain  the  necessary  length  of  plane  for  supporting 
heavy  weights,  the  surfaces  may  be  superposed,  or  placed  in  parallel  rows, 
with  an  interval  between  them.  A  dozen  pelicans  may  fly  one  above  the 
other  without  material  impediment;  as  if  framed  together;  and  it  is 
thus  shown  how  two  hundredweight  may  be  supported  in  a  transverse 
distance  of  only  ten  feet.1' 


150  VEHICLES  OF  THE  AIR 

and  the  sons  of  Bishop  Wright  of  that  city,  began 
devoting  a  large  portion  of  their  time  to  the  serious 
development  of  such  previous  aeronautical  knowl- 
edge as  they  found  available,  their  first  interest  in 
the  subject  having  been  awakened  by  flying  toys 
years  before,  and  a  fresh  impetus  having  been 
given  it  by  the  death  of  Lilienthal,  which  directed 
attention  to  his  work,  in  1896.  Proceeding  with 
the  sound  idea  that  actual  practice  in  the  air  was 
the  surest  road  to  success,  an  idea  that  had  been 
fully  appreciated  but  little  realized  by  others,  the 
Wrights  levied  upon  every  possible  source  of  infor- 
mation and,  frankly  commencing  with  Chanute's 
help  and  a  modification  of  the  Chanute  biplane 
glider,  which  they  regarded  as  the  most  advanced 
construction  existent  at  the  time,  they  entered  upon 
a  deliberate,  unremitting,  and  enthusiastic  prosecu- 
tion of  an  at  first  thankless  task,  which  for  sturdy 
perseverance  in  the  face  of  obstacles  and  sensible 
disregard  of  ignorant  opinions,  has  few  parallels  in 
the  history  of  invention. 

Having  from  the  outset  more  faith  in  experi- 
mental than  in  analytical  methods,  the  Wrights  set 
themselves  first  to  the  task  of  confirming  or  cor- 
recting the  various  formulas  of  their  predecessors 
concerning  wind  pressures,  the  sustaining  effects  of 
different  inclined  surfaces,  etc.  Progressing  from 
these  to  the  various  possible  methods  of  steering, 
and  of  maintaining  lateral  and  longitudinal  bal- 
ance, they  tirelessly  tested  a  constantly  improving 
series  of  constructions  by  hundreds  of  kite  and 
gliding  experiments  conducted  among  the  sand 


HEAVIER-THAN-AIR  MACHINES         151 

dunes  near  Kitty  Hawk,  North  Carolina.  Having 
thus  secured  an  amount  of  practice  that  enabled 
them  to  make  Reasonably  safe  gliding  flights  of 
considerable  length  in  calms  and  moderate  winds, 
they  next  undertook  the  application  of  a  motor, 
naturally  turning  to  automobile  mechanism  as  the 
most  promising  source  of  a  suitable  power  plant. 
This  resulted,  on  December  17, 1903,  in  four  flights 
in  calm  air  with  a  gasoline  engine,  the  longest  o£ 
which,  however,  was  of  only  852  feet — shorter  than 
many  of  Lilienthal's  glides  prior  to  1896,  hardly 
a  fourth  as  long  as  the  flight  of  Langley's  model 
on  May  6,  1896,  and  not  quite  as  long  as  the  flight 
of  Ader  with  his  "Avion",  on  October  14,  1897. 
On  March  22,  1903,  a  United  States  patent  was 
applied  for  on  a  wing-warping  device,  in  combina- 
tion with  flat  sustaining  surfaces,  indicating  either 
a  failure  at  this  time  to  appreciate  fully  the  abso- 
lute importance  of  definitely  and  correctly  curved 
surfaces,  or  else  constituting  a  lack  of  the  "full 
disclosure"  demanded  by  patent  law.  The  construc- 
tion described  in  the  patent  specifications  (see  Fig- 
ure 259)  being  obviously  inoperative,  these  were 
repeatedly  objected  to  and  rejected  by  the  patent- 
office  examiners,  and  it  was  not  until  May  22, 1906, 
that  the  claims  were  allowed — even  then  on  the 
basis  of  an  inoperative  construction. 

Throughout  1904  the  Wright  experiments  con- 
tinued, surrounded  by  the  utmost  secrecy,  but  it 
is  definitely  attested  by  Chanute  that  during  this 
year  they  increased  the  length  of  their  longest  flight 
to  1,377  feet. 


152  VEHICLES  OF  THE  AIR 

It  was  not  until  nearly  the  end  of  September, 
1905,  months  after  Montgomery's  flights  in  the 
Santa  Clara  Valley  and  publication  of  his  con- 
struction, and  some  time  after  his  patent  was  ap- 
plied for,  that  the  Wrights  commenced  to  be  con- 
spicuously successful — with  parabolically-curved 
sustaining  surfaces  and  a  system  of  wing- warping 
closely  resembling  that  of  Montgomery's  patent 
and  not  at  all  like  that  claimed  in  the  Wright 
patent  (see  Figure  260).  Following  these  successes, 
which  though  well  authenticated  were  kept  out  of 
the  newspapers  and  well  away  from  the  general 
public,  vigorous  but  quiet  efforts  were  made  during 
1906  and  1907  to  sell  to  European  governments,  not 
patent  rights,  but " secrets"  of  construction.  Little 
success  resulting,  because  of  the  terms  and  condi- 
tions that  were  stipulated,  and  European  aviators 
having  by  this  time  progressed  to  the  point  of  mak- 
ing long  flights,  this  policy  was  abandoned  late  in 
1908,  and  the  Wrights  came  out  into  the  open  with 
their  machines — Orville  Wright  in  the  United 
States  and  Wilbur  Wright  in  France — with  the  re- 
sult that  they  were  quickly  able  to  establish  new 
distance  and  duration  records,  which  stood  for 
nearly  a  year.  At  the  present  time,  however,  the 
Wright  machine  does  not  hold  a  single  distance, 
duration,  speed,  weight-carrying,  cross-country,  or 
altitude  record  in  the  world,  and  has  borne  out  the 
rather  numerous  critics  of  its  construction  by  being 
responsible  for  an  undue  proportion  of  the  acci- 
dents that  have  occurred  in  the  history  of  power- 
propelled  heavier-than-air  machines. 


HEAVIEE-THAN-AIR  MACHINES        153 

VOISIN  BEOTHEKS 

In  the  course  of  the  early  Bleriot  and  Arch- 
deacon experiments  over  the  Seine  with  towed  and 
free  gliders  during  1904,  much  of  the  most  success- 
ful construction  and  designing  work  was  done  by 
Gabriel  Voisin,  a  young  French  engineer  who  sub- 
sequently, in  association  with  his  brother,  of  the 
firm  now  known  as  Voisin  Freres, 
and  of  their  engineer,  M.  Colliex, 
designed  the  excellent  machines 
of  box-kite  type  with  which  Far- 
man  and  Delagrange  electrified 
the  world  by  their  flights  in  the 
latter  part  of  1907  and  the  fore- 
part of  1908.  The  Voisin  ma- 
chines, which,  while  not  without 
serious  shortcomings,  possess  a  considerable  degree 
of  automatic  stability,  are  the  prototypes  of  the 
highly  successful  Farman  machine. 

MISCELLANEOUS 

In  addition  to  the  foregoing,  those  among  the 
world's  aeroplane  designers  who  are  most  worthy 
of  mention  are  Alexander  Graham  Bell,  inventor 
of  the  telephone  and  founder  of  the  Aerial  Experi- 
ment Association,  and  whose  tetrahedral  kite  is  a 
construction  of  great  originality  and  interest ;  S.  F. 
Cody,  designer  of  one  of  the  most  successful  man- 
lifting  kites,  and  whose  biplane  (see  Figure  202)  is 
the  largest  and  one  of  the  most  successful  aero- 
planes that  has  ever  flown ;  Glenn  H.  Curtiss,  whose 
flights  with  the  "June  Bug"  and  "Silver  Dart" 


154  VEHICLES  OF  THE  AIR 

of  the  Aerial  Experiment  Association,  and  with 
machines  of  his  own,  entitle  him  to  front  rank 
among  aviators;  Danjard,  who  in  1871  designed 
what  was  perhaps  the  first  double  monoplane, 
which  proved  unsuccessful  chiefly  because  of  the 
lack  of  a  suitable  motor;  Count  D'Esterno,  who  in 
1864  wrote  a  remarkable  pamphlet  in  which  he 
suggested  a  form  of  wing  warping  and  proposed 
other  details  since  proved  of  practical  value, 
though  he  died  in  1883,  before  the  completion  of  a 
machine  that  was  then  under  construction ;  Robert 
Esnault  Pelterie,  the  young  French  engineer  whose 
first  work  began  some  years  ago  and  whose  speedy 
and  ingenious  monoplane  is  regarded  as  one  of  the 
most  successful  and  promising  of  present  machines, 
besides  which  it  has  sustained  the  highest  weight 
per  unit  of  area  of  any  machine  yet  flown  success- 
fully ;  Henry  Farman,  whose  early  flights  with  the 
Voisin  machines,  subsequent  development  of  this 
type  into  the  first  aeroplane  to  employ  both  wheels 
and  runners  in  the  starting  and  alighting  gear,  and 
his  recent  record  achievements,  have  definitely  con- 
tributed to  progress;  Captain  Ferdinand  Ferber, 
of  the  French  army,  who  ranks  equally  high  as  a 
pioneer  worker,  as  an  authority  on  both  heavier- 
than-air  and  lighter-than-air  craft,  and  as  a  writer 
on  the  subject  of  aeronautics,  and  whose  tragic 
death  some  months  ago  is  one  of  the  heaviest  tolls 
yet  exacted  for  aeronautical  advancement;  Lau- 
rence Hargrave,  whose  invention  of  the  box  kite 
and  wonderful  work  with  ornithopter  propulsion 
have  in  a  measure  overshadowed  his  discoveries 


HEAVIER-THAN-AIR  MACHINES        155 

concerning  the  aeroplane  proper;  Henson,  whose 
immense,  3000-pound  aeroplane  built  in  1842,  em- 
bodied a  large  proportion  of  the  features  since 
proved  needful,  and  turned  out  a  failure  more  be- 
cause it  was  too  much  in  advance  of  its  time  than 
for  any  other  single  reason ;  A.  M.  Herring,  whose 
early  association  with  Chanute  and  recent  asso- 
ciation with  Curtiss  at 
least  entitles  him  to  rec- 
ognition ;  Captain  Le 
Bris,  whose  reputed  as- 

FIGOBK  36.— Le  Brig'  Glider. 

tounding    flight    in 

France  with  a  wing- warped  machine  in  1867  almost 
staggers  belief  (the  Le  Bris  glider  is  illustrated 
in  Figure  36)  ;  M.  Levavasseur,  whose  Antoinette 
monoplanes  are  among  the  finest  present-day  fliers 
and  are  certainly  the  most  graceful,  and  whose 
fuel-injection  motors  have  been  used  to  a  greater 
or  less  extent  in  nearly  every  modern  European 
aeroplane  of  demonstrated  quality;  Linfield,  who 
in  1878  conceived  the  ingenious  plan  of  testing  the 
lift  of  an  aeroplane  by  hauling  it  on  a  railway  flat 
car,  and  thus  caused  it  to  rise  clear — though  with- 
out contributing  anything  to  the  solution  of  equi- 
librium ;  Michael  Loup,  who  in  1852  had  fully  de- 
veloped the  wheeled  starting  gear;  Hiram  S. 
Maxim,  whose  exhaustive  and  expensive  experi- 
ments in  1894  gave  definite  solution  of  the  power 
and  lifting  problems,  though  they  were  of  little 
help  to  seekers  after  efficiency  and  equilibrium; 
Louis  Pierre  Mouillard,  whose  "L  'Empire  de 
1'Air",  published  in  1881,  is  one  of  the  great 


15C 


VEHICLES  OF  THE  AIR 


classics  of  aeronautical  literature,  whose  gliding 
flights  in  Egypt  are  not  without  interest,  and  whose 
United  States  patent  (see  Figure  262)  shows  a 
tolerably  clear  appreciation  of  one  type  of  wing 
warping;  Thomas  Moy,  who  in  1875  got  12  miles 
an  hour — on  the  ground — by  the  thrust  of  the 
propellers  of  his  " aerial  steamer"  (see  Figure  37)  ; 


FIGUBB  37. — Moy's  Aerial  Steamer.  Tested  on  a  track  in  the  Crystal 
Palace,  London,  in  June,  1875.  Six-foot  propellers.  Steam  engine,  2*&x3-inch 
cylinder,  developing  three  horsepower  at  550  revolutions  a  minute.  Engine 
weighed  80  pounds,  with  boiler.  Car  ran  on  three  small  wheels.  Speed  of 
12  miles  an  hour  proved  insufficient  to  lift. 

Horatio  Phillips,  who  in  the  years  from  1884  to 
1891  by  empirical  methods  went  more  deeply  into 
the  question  of  correct  wing  sections  than  any  pre- 
vious investigator  and  then  produced  slat-like 
multiplane  models  of  extraordinary  lifting  capaci- 
ties; Stringfellow,  who  in  1868  built  the  first  tri- 
plane  (a  model)  and  afterwards  produced  a  steam- 
engine  that  developed  one  horsepower  within  13 


HEAVIER-THAN-AIR  MACHINES        157 

pounds  of  weight,  achievements  that  he  was  follow- 
ing up  by  the  construction  of  a  man-carrying  ma- 
chine, which  was  left  unfinished  at  his  death  in 
1883;  Victor  Tatin,  who  made  in  1879  the  first 
model  aeroplane  that  lifted  itself  by  a  run  on  the 
ground,  and  who  at  a  recent  date  was  working  on 
a  modern  aeroplane  for  the  Clement-Bayard  con- 
cern, in  France ;  and  Vuia,  who  in  1906  designed 
one  of  the  earliest  of  the  really  modern  monoplanes, 
and  accomplished  a  few  very  short  flights  towards 
the  end  of  this  year  and  during  1907. 


CHAPTER  FOUR 

AEROPLANE  DETAILS 

Passing  from  the  contemplation  of  the  broader 
possibilities  and  problems  of  human  flight  to  con- 
sideration of  the  means  by  which  such  flight  is  to 
be  accomplished  is  necessarily  a  transition  from 
the  general  to  tbe  particular. 

Aeroplanes,  for  example,  are  vehicles  involving 
sustaining  surfaces  of  suitable  form,  provided 
with  means  for  propulsion,  for  the  maintenance 
of  equilibrium,  and  for  steering  in  different  lateral 
and  vertical  directions.  Evidently  the  provision 
of  these  different  elements  can  be  carried  out  in 
a  great  variety  of  ways,  which  being  the  case  it 
is  possible  to  work  towards  the  more  perfect  de- 
signs only  by  two  policies — one  requiring  study 
of  the  laws  involved  in  flight  and  the  application 
of  these  laws  in  suitable  mechanisms,  and  the  other 
involving  observation  and  copying  of  the  flying 
mechanisms  of  nature.  Both  of  these  policies  are 
beset  by  tremendous  difficulties — the  first  because 
of  the  exceedingly  complex  factors  of  the  problem, 
and  the  second  because  there  is  no  bird  that  ap- 
proaches in  size  or  weight  the  smallest  man-carry- 
ing vehicle. 


158 


FIGURE  69. — Goupy  Biplane.  In  this  the  placing  of  the  surface  v  in  advance  of  the 
surface  w  is  intended  to  cause  the  air-currents  to  meet  the  surfaces  in  such  a  manner  as  to 
secure  greater  lift  from  the  upper  surface  than  is  secured  in  biplanes  in  which  it  is  placed 
farther  back.  That  flatness  of  the  surfaces  is  quite  erroneous,  though  perhaps  not  the  only 
reason  the  machine  failed  as  a  flier. 


FIGURE  71. — Internal    Framing   of    Antoinette    Monoplane    Wing. 


FIGURE  72. — Framing  of  Antoinette  Wing  Inverted.  The  load  is  supported  on  the  two 
main  girders  aa,  which  are  connected  by  a  maze  of  crossbraces  to  the  transverse  ribs  and 
secondary  longitudinal  members. 


AEROPLANE  DETAILS  159 

ANALOGIES  IN  NATURE 

Besides  constituting  the  most  conclusive  evi- 
dence imaginable  of  the  perfect  practicability  of 
flight,  as  well  as  serving  as  the  original  and  a  con- 
stant stimulus  to  man  in  his  efforts  to  achieve  navi- 
gation of  the  air,  the  birds  and  other  animals  that 
fly  afford  models  that  naturally  merit  the  most 
thorough  and  profound  consideration  of  all 
students  of  aerodynamics.  For  in  nature's 
mechanisms  of  flight  must  exist  answers  to  all  the 
problems  of  flying,  awaiting  for  their  discovery 
only  the  analyses  and  applications  of  sufficiently 
persevering  and  painstaking  investigators. 

From  the  facts  of  animal  flight  there  are  cer- 
tain broad  deductions  to  be  made  at  the  outset. 
Perhaps  the  most  impressive  of  these  is  the  evident 
fact  that  there  is  more  than  one  way  and  more 
than  one  type  of  mechanism  that  can  be  made  to 
serve  the  purpose.  There  are  the  common  flap- 
ping flight,  the  less-common  soaring  flight,  and 
the  flight  of  the  wing-case  insects,  while  in  the 
way  of  structural  variety  it  is  a  broad  range  from 
the  tissues  of  insect  wings,  the  furred  skin  folds 
of  the  flying  squirrel,  and  the  membranous  integu- 
ments of  the  flying  fishes,  bats,  etc.,  to  the  feath- 
ered perfection  of  the  wing  of  a  humming  bird  or 
condor. 

The  size  of  flying  animals  also  is  a  point  of 
interest.  Perhaps  the  heaviest  of  the  soaring  fliers 
is  the  California  vulture,  similar  to  but  in  its 
largest  specimens  larger  than  the  largest  speci- 


160  VEHICLES  OF  THE  AIR 

mens  of  the  Andean  condor,  and  not  uncommonly 
weighing  as  much  as  20  pounds.  Turkeys  are  said 
sometimes  to  weigh  twice  this,  while  the  albatross 
is  occasionally  found  of  a  weight  of  18  pounds. 
Still  heavier  than  these  may  have  been  the  extinct 
pterodactyl,  which  it  is  more  than  probable,  how- 
ever, weighed  no  more  than  30  pounds.  No  flying 
creature  that  ever  existed  appears  to  have  been  as 
heavy  as  the  combination  of  a  man  with  the  lightest 
structure  that  can  be  made  to  support  him,  and 
this  fact  often  has  been  cited  as  an  argument 
against  the  possibility  of  human  flight,  having  been 
advanced  as  conclusive  by  no  less  an  authority 
than  the  late  Simon  Newcomb.  But  in  this  con- 
nection it  is  a  significant  fact  that  the  areas  and 
the  power  required  to  support  a  given  weight 
steadily  decrease  in  passing  from  the  smaller  fly- 
ing animals  to  the  larger.  This  point,  so  favorable 
in  its  bearings  on  the  problems  of  human  flight,  is 
not  wholly  due  to  any  single  cause,  though  prob- 
ably th#  main  factors  are  the  effect  noted  on  Page 
184,  and  the  escape  of  air  around  the  edges  of  wing 
surfaces —  such  edges  being  necessarily  longest  in 
proportion  to  the  area  in  the  smaller  sizes,  it  being 
a  geometrical  axiom  that  the  length  of  boundary 
of  any  given  shape  of  surface  increases  in  direct 
ratio  with  increases  in  linear  dimensions,  whereas 
areas  increase  with  the  square  of  these  dimensions. 
Thus  a  square  one  by  one,  equalling  one  square 
unit  of  area,  has  four  linear  units  of  edge — one 
foot  to  each  one-fourth  of  a  square  unit  of  area, 
whereas  a  square  two  by  two,  affording  four  square 


AEROPLANE  DETAILS  161 

units  of  area,  has  only  eight  linear  units  of  edge — 
one  to  each  one-half  of  a  square  unit  of  area. 

The  weights,  weight  supported  per  unit  of  wing 
area,  horsepower,  pounds  supported  per  unit  of 
area,  and  pounds  supported  per  horsepower,  in 
the  cases  of  different  flying  creatures  and  success- 
ful aeroplanes,  are  given  in  tabular  form  on  the 
next  page. 

FLYING  FISH 

Flying  fish,  which  are  found  in  all  the  warmer 
seas,  are  capable  of  maximum  flights  of  only  a  few 
hundred  yards — usually  at  a  height  of  not  over 
fifteen  feet — by  a  method  of  progression  that  is 
decidedly  peculiar  and,  in  some  respects,  suffi- 
ciently mysterious  to  lead  to  controversy  amongst 
different  observers.  It  is 
generally  supposed  that 
the  flight  is  of  the  true 
gliding  type,  dependent 
altogether  upon  the  force 

Of    the    initial    impulse    Of  FIGURE  38.— Flying  Fish. 

the  tail  in  the  rush  out  of 

the  water  when  these  creatures  are  pursued  by  any 
of  their  numerous  enemies,  but  there  are  not  lack- 
ing those  who  stoutly  assert  that  there  is  on  occa- 
sion a  true  flapping  flight.  This  has  been  explained 
by  others  as  a  fluttering  of  the  great  pectoral  fins 
into  successive  wave  crest\  to  keep  the  membranes 
from  drying  in  long  flights.  It  is  also  commonly 
stated  that  flying  fish  go  much  farther  against  the 
wind  than  with  it — which  if  true  at  once  involves 
the  difficult  and  little  understood  phenomena  of 


TABULAR  COMPARISON  OF  FLYING  ANIMALS  AND  AEROPLANES. 


In" 

•o 

j! 

u 

Wing  Area 
(square  feet) 

Horse- 
power 

Pounds  to 
Square  Foot 

Pounds  per 
Horsepower  jj 

*Cabbage    Butterly    

00016*) 

00942 

0179 

Gnat   ... 

0000006 

AAAAO 

..... 

O2rt4 

*  Maiden   Dragon   Fly.  .  . 

0004°3 

01415 



AOQO 

.... 

Swallow-Tailed  Butterfly    . 

.000718 

01137 

0631 

.... 

Flat-Bellied  Dragon  Fly  

00128 

0135 

0948 

.... 

House  Fly  

000021 

000183 

..... 

1147 

.... 

0078 

0507 

153 

.... 

Cockchafer    



195 

Stag  Beetle    (female)  

.214 

Sphinx   Moth    .  . 

00405 

01892 

2140 

Stag    Beetle    (male)  

266 

Rhinoceros   Beetle    

318 

Swallow               .... 

038 

1116 

349 

Honey   Bee        

.000156 

000396 

..... 

3939 

.... 

Screech  Owl    

424 

.... 

Short-Bared  Owl    

.446 

Swift          ... 

.0708 

1462 

484 

535 

Humming    B'rd 

015 

026 

001 

577 

15 

Langley  Double  Monoplane.  .  .  '. 
•Laughing  Gull    

30. 

52. 

1.5 

.577 
62 

20 

Glossy   Ibis    

.649 

Sparrow     .    . 

059 

0791 

747 

Pilcher  Glider  (the  "Gull")  .... 

75 

.763 

*Sparrow    Hawk 

549 

69 

79 

Bumble    Bee    

.00093 

.00104 

8942 

*Herring   Gull    

2.18 

2.41 

.9 

Fishhawk 

9°6 

Crow    .  .    

1  25 

1  3 

96 

Dove     

.619 

.617 

1. 

*  Stork 

4  78 

4  57 

1  04 

*Scavenger  Vulture                  .  . 

1  052 

*Turkey    Buzzard    

1.052 

*White   Pelican 

1  052 

Montgomery  Monoplane  Glider 

200. 

185. 

1.08 

Thrush         

.211 

.188 

1.12 

Lilicnthal  Biplane  Glider  

200. 

170. 

1.18 

*Pterodactyl          .        

30. 

25. 

.030 

1  2 

|833 

Wright  Biplane  Glider  

238. 

290. 

1.22 

Wright  Biplane  Glider 

210 

160 

1  31 

*Sea  Eagle          

10.57 

8.05 

1.31 

Pilcher  Glider  (the  "Hawk").. 

215. 
1. 

165. 
.7 

.6i2 

1.33 

1.429 

83 

1.456 

*Eared   Vulture    

1.456 

Curtiss  Biplane    

550. 

350. 

25. 

1.57 

16 

17. 

9.85 

.043 

1.726 

f395 

*Flying  Fox            

2.91 

1.65 

1.76 

540. 

9. 

60 

1.  818 

Voisin  Biplane            

1150. 

597. 

50. 

1.93 

23 

800. 

410. 

45. 

1.95 

17 

Partridge     

.67 

.34 

1.97 

Wright   Biplane          

1200. 

560. 

25. 

2.04 

48 

2000. 

950. 

80. 

2.1 

25 

T  ilirnthnJ    \fnnrtnlanf   Glider 

180 

85 

2  11 

Antoinette   Monoplane    

730. 

324. 

50. 

2.25 

15 

Pheasant                    

2.11 

.89 

2.37 

Wright   Biplane    

1200. 

450. 

28. 

2.66 

43 

1540. 

537. 

50. 

2.86 

31 

Antoinette   Monoplane        

1110. 

370. 

50. 

3. 

22 

•  Albatross                        

25.36 

8.12 

3.12 

20.29 

6.02 

3.36 

REP    Monoplane           

933. 

168. 

30. 

5.55 

81 

Wild  Goose                  

9. 

2.65 

.026 

3.396 

t34« 

Santos-Dumont  Monoplane 
Bleriot  Monoplane  #o    11  
Bleriot  Monoplane  No.  IS  

400. 
715. 
1100. 

115. 
150. 
216. 

35. 
35. 
30. 

3.47 
4.76 
5.1 

11 
11 
36 

*  Soaring  Fliers. 


tNot«  the  great  efficiency  of  the  bird  mechanism. 
162 


AEROPLANE  DETAILS  163 

soaring  flight.  An  exceedingly  interesting  fact 
about  flying  fish  is  that  they  present  the  only 
examples  in  nature's  fliers  of  the  use  of  vertical 
surfaces — presumably  to  afford  automatic  lateral 
stability  (see  Page  209).  The  largest  flying  fish 
are  about  18  inches  long  (see  Figure  38). 

FLYING  LIZAKDS 

The  Malayan  gecko,  or  "flying  dragon",  is  a 
curious  creature,  the  habits  of  which  are  little 
known.  It  is  provided  with  loose  membranous 
expansions  along  the  sides  of  the  body  which  are 
supposed  to  enable  it  to  make  long  gliding  leaps, 
like  those  of  the  flying  squirrels.  A  commoner 
lizard  of  East  India  has  loose  folds  of  skin  that 
are  distensible  by  several  movable  ribs.  Neither 
of  these  animals  attains  a  length  of  more  than 
eight  inches. 

FLYING  SQUIRRELS 

The  common  flying  squirrel  is  a  very  small 
nocturnal  species  with  a  feather-like  tail,  and  folds 
of  skin  on  either  side  capable  of  being  stretched 
out  and  controled  in  such  manner  by  the  legs  that 
60-foot  glides  from  treetops  are  made  in  safety. 
There  are  much  larger  but  less  known  species  in 
California  and  Alaska  that  undoubtedly  can  glide 
from  trees  200  feet  high. 

FLYING  LEMUR 

The  flying  lemur,  the  "colugo"  of  the  East 
Indies,  has  a  very  loose  skin  with  peculiarly  sleek 
fur,  enabling  it  to  make  long  sailing  leaps  like  the 


164 


VEHICLES  OF  THE  AIR 


flying  squirrel.  It  is  a  slender  creature  18  inches 
long,  and  is  much  the  largest  and  heaviest  of  the 
several  animals  that  glide  in  this  manner. 

FLYING  FEOG 

An  animal  of  which  there  has  been  little  if  any 
accurate  observation  is  the  flying  frog — a  Malayan 

tree-  dwelling  frog 
that  is  supposed  to 
sail  down  from  the 


FIGURE  39. — Flying  Frog.  Without 
being  confirmed  by  observation,  it  never- 
theless appears  obvious  that  this  curious 
creature  can  maintain  its  lateral  and 
longitudinal  balance  only  by  differential 
tilting  of  the  side  pairs  of  feet  in  the 
first  case  and  of  the  front  and  rear  pairs 
in  the  second. 


ing  flights.     Its  feet 
are    very    large    and 
webbed   between   the 
toes  (see  Figure  39). 
It  is  peculiarly  inter- 
esting as  a  perfect  ex- 
ample of  correct 
methods  of  maintain- 
ing lateral  and  longitudinal  balance  by  the  manip- 
ulation of  a  plurality  of  separated  surfaces  (see 
Page  215), 

SOAKING  BIEDS 

The  phenomena  of  soaring  flight  has  long  been 
a  mystery  to  students  of  the  subject,  having  baf- 
fled the  most  eminent  physicists  in  attempts  to 
explain  it  and  defied  the  most  painstaking  observ- 
ers to  disprove  its  existence.  For  these  reasons 
the  effortless  travel  of  the  soaring  birds,  the 
largest  and  practically  the  heaviest  of  all  flying 
creatures,  is  regarded  as  the  ultimate  achievement 
in  aerial  navigation — to  be  attained  by  man,  if  at 


FIGURE  73. — Frame  of  Bleriot  Monoplane  Wing.  In  this  wing  the  longitudinal  supporting 
members  are  five  in  number,  with  cross  bracing  and  curved  ribs  similar  to  those  used  in  the 
Antoinette  machine.  The  curvature  is  given  to  the  ribs  simply  by  straining  them  into  place 
as  the  structure  is  put  together,  there  being  no  preliminary  bending. 


-  '- 


FIGURE  74. — Inverted  Upper  Wing  Frame  of  Wright  Biplane.  This  frame  is  inverted 
on  supports  for  the  convenience  of  men  working  upon  it.  It  is  to  be  noted  that  each  rib  is 
made  of  two  light  strips  66,  which  are  spaced  apart  by  the  wing  bars  aa  and  by  the  small 
spacing  members  eld.  The  rib  in  the  foreground  is  made  solid  because  it  forms  the  end  of 
a  section  of  the  wing,  which  attaches  to  an  adjacent  section  by  the  small  clamping  plates 
on  the  ends  or'  the  wing  bars. 


" 
I  V   «*" 


AEROPLANE  DETAILS  165 

all,  only  upon  a  complete  and  perfect  understand- 
ing of  laws  that  neither  fit  into  nor  follow  from 
many  of  the  accepted  conceptions  of  force  and 
motion  (see  Page  169).  In  the  table  on  Page  162 
the  soaring  birds  are  designated  with  stars — *. 
The  most  conspicuous  features  to  be  discerned  in 
a  study  of  soaring-bird  forms  are  the  usually  ex- 
treme length  and  narrowness  of  the  wings,  the 
lower  sustention  per  unit  of  area  than  prevails 
with  flapping  fliers,  and  a  pronouncedly  different 
type  of  curvature  to  the  wing  sections. 

SOAKING  BATS 

Most  of  the  bats  are  flapping  fliers,  but  the 
"flying  fox",  or  "kalong",  of  Java,  which  is  one 
of  the  largest  of  its  kind,  sometimes  measuring  5 
feet  from  tip  to  tip,  practises  true  soaring  flight. 
This  fact  is  of  interest  chiefly  in  that  it  refutes  the 
assertions  of  the  few  theorists  who  contend  that 
soaring  flight  requires  for  its  accomplishment  a 
supposed  imperceptible  movement  of  feathers. 

THE  PTERODACTYL 

This  bird-like  reptile  (see  Figure  40),  which 
is  known  only  from  the  discovery  of  fossil  remains 
in  strata  of  the  Cretaceous  period,  measures  in 
ordinary  specimens  about  20  feet  from  tip  to  tip. 
It  must  have  been,  however,  very  light,  the 
wing  bones  that  have  been  found  being  mere  shell- 
like  tubes  of  large  diameter  and  extreme  thinness. 
The  fact  that  there  once  existed  a  larger  flying 
animal  than  any  now  extant  has  been  held  to  prove 


166 


VEHICLES  OF  IRE  AIR 


FIGURE  40. — Comparison  of  Pterodactyl  and  Condor.  The  extinct  pterodactyl, 
a  great  flying  reptile  the  fossilized  remains  of  which  have  been  found  in 
strata  of  the  Cretaceous  period,  is  the  largest  flying  creature  of  which  we 
have  any  knowledge.  Its  wing  spread  was  20  feet,  but  its  maximum  weight 
was  possibly  not  over  30  pounds. 

a  greater  density  to  the  earth's  atmosphere  in  pre- 
historic times,  but  this  theory  is  neither  necessary 
as  an  explanation  nor  borne  out  in  the  evidence. 

FLYING  INSECTS 

It  is  surprising  how  generally  students  of  flight 
have  overlooked  that  fact  that  in  certain  insects 
there  seems  to  be  an  exceedingly  close  parallel  to 

modern  aeroplane  construc- 
tions, in  which  there  ap- 
pears primarily  a  sustain- 
ing surface  moved  through 
the  air  at  an  angle  of  inci- 
dence   and    secondarily    a 
4i.-wmg.case  insect   separate    polling   ele- 
ment.   This  combination  is  peculiar  to  insects  with 
wing  cases",  of  the  order  coleoptera,  in  which 


u 


AEROPLANE  DETAILS  167 

during  flight  the  wing  covers  are  rigidly  extended 
at  right  angles  to  the  line  of  movement,  while  the 
under  wings  are  rapidly  vibrated  to  produce  pro- 
pulsion, as  is  suggested  in  Figure  41.  The  largest 
known  insects  that  use  this  mode  of  flight  have  a 
wing  span  of  not  over  6  inches. 

MONOPLANES 

This  general  type  of  supporting  surface,  being 
that  used  by  all  flying  animals,  is  on  this  ground 
reasonably  to  be  regarded  as  the  superior  form, 
besides  which  it  is  a  safe  assertion,  despite  various 
conspicuous  successes  that  have  been  achieved 
with  biplanes  and  occasional  triplanes,  that  at  the 
present  time  no  aerial  vehicle  ever  built  has 
afforded  results  more  promising  or  significant  than 
those  apparent  in  the  remarkable  equilibrium  and 
extraordinarily-flat  gliding  angles  of  the  Mont- 
gomery machine  (see  Page  139),  and  in  the  high 
sustention  per  unit  of  area  in  the  Bleriot  and 
E.  E.  P.  machines  (see  Page  162). 

For  reasons  that  are  elsewhere  explained 
herein  (see  Pages  168  and  169),  a  monoplane  will 
afford  more  sustention  per  unit  of  surface  than  can 
be  expected  from  each  of  two  or  more  similar  sur- 
faces placed  one  above  the  other — unless  an  alto- 
gether impracticable  amount  of  separation  be  used. 

The  chief  objection  so  far  urged  against  the 
monoplane  is  the  supposed  difficulty  of  staying  the 
wing  surfaces  properly,  the  trussed  construction 
of  the  biplane  naturally  being  not  available.  Yet 
one  has  only  to  examine  the  internal  trussing  of 


168  VEHICLES  OF  THE  AIR 

the  Antoinette  monoplane  (see  Figures  71  and  72), 
or  the  simple  staying  of  the  Bleriot  and  Montgom- 
ery wing  surfaces,  to  realize  that  with  this  con- 
struction there  are  ways  and  means  of  achieving 
results  quite  as  successful  as  any  that  can  be  had 
with  others. 

MULTIPLANES 

The  first  suggestion  of  the  multiplane  was  made 
by  F.  H.  Wenham,  in  his  paper  read  at  the  first 
meeting  of  the  Aeronautic  Society  of  Great 
Britain,  in  1868,  which  is  quoted  on  Page  149. 

It  is  obvious  that  any  number  of  superimposed 
planes  can  conceivably  be  used,  as  was  suggested 
in  the  decidedly  freakish  " Venetian-blind"  con- 
struction of  Phillips  (see  Page  157),  but  so  far 
the  most  successful  results  have  been  obtained 
with  not  more  than  two  planes,  this  number  afford- 
ing all  the  possible  advantages,  of  trussed  construc- 
tion with  a  minimum  of  its  disavantages.  It  is 
a  serious  though  at  the  present  time  little  regarded 
objection  to  multiplanes  that  they  increase  the 
necessity  for  always  maintaining  headway  to  main- 
tain sustention.  Thus,  if  a  biplane  starts  to  drop 
vertically,  in  its  normal  position,  it  can  oppose 
only  half  of  its  total  area  to  resist  the  fall.  Car- 
ried to  its  extreme  the  result  must  be  something 
like  the  Phillips  slat-like  machine,  which  without 
forward  movement  would  drop  like  a  brick.  On 
the  other  hand,  the  Montgomery  monoplane  glider 
can  be  released  in  the  air  wholly  without  forward 
movement,  in  which  case  it  simply  settles  slowly 


AEROPLANE  DETAILS  169 

as  it  commences  to  glide.  Much  the  same  is  true 
of  any  monoplane,  unless  the  loading  per  unit  of 
area  is  carried  to  extremes. 

BIPLANES 

The  biplane  is  of  particular  interest  as  being 
the  type  of  machine  with  which  Lilienthal  was  ex- 
perimenting when  killed,  the  type  of  glider  with 
which  Chanute  attained  the  greatest  success,  and 
the  form  of  flying  machine  which  has  developed  to 
a  high  degree  in  the  Wright,  Voisin,  Curtiss,  and 
Farman  constructions — not  to  mention  the  close 
and  significant  analogy  it  finds  in  the  box  kite. 

MOKE   THAN   TWO   SUEFACES 

The  only  multiplanes  that  ever  have  accom- 
plished any  really  successful  flying  at  the  present 
writing  are  the  Vaniman  triplane  and  the  Voisin- 
Farman  triplane,  the  latter  illustrated  in  Figure 
211.  Both  have  been,  however,  discarded  for  re- 
turns to  the  biplane  construction. 

FORMS  OF  SURFACES 

It  is  perfectly  evident  to  any  one  of  most  ordi- 
nary engineering  attainments  that  the  only  pos- 
sible complete  and  thoroughly  logical  method  of 
treating  the  subject  of  wing  forms  and  related  air 
reactions  is  the  mathematical,  but  since  aerody- 
namics involve  perhaps  the  most  difficult,  obscure, 
and  least-investigated  and  understood  of  all  the 
phenomena  of  force  and  motion,  it  is  out  of  the 
question  in  the  present  state  of  the  science  to  offer 


170  VEHICLES  OF  THE  AIR 

final  and  definite  explanations  of  principles  in- 
volved. The  most  that  may  be  reasonably  at- 
tempted is  to  marshal  connectedly  the  empirical 
deductions  that  have  been  reached,  to  state  the 
few  generalizations  that  seem  reliable,  and  to  give 
space  to  the  opinions  of  the  most  advanced  authori- 
ties on  the  subject.* 

Certainly  it  must  become  evident  upon  the  most 
casual  investigation — upon  the  least  reading  of  the 
great  mass  of  speculation  and  attempted  analyses 
of  aerodynamic  reactions — that  nearly  all  of  the 
workers  in  this  field  have  been  struggling  in  the 
dark,  and  that  their  conclusions,  when  not  wholly 
worthless,  are  as  a  rule  to  be  accepted  only  in  part 
or  with  many  reservations.  An  example  of  this 
appears  in  a  recent  issue  of  a  well-known  aeronau- 
tical journal,  in  which  there  appears  an  article  by  a 
writer  evidently  well-versed  in  modern  physical 
science  and  related  modes  of  mathematical  reason- 
ing. Yet,  at  the  end  of  a  labored  dissertation — in 
which  it  is  attempted  to  show  that  the  arc  of  a  cir- 
cle traveling  along  a  line  tangent  to  the  advancing 
edge  is  the  correct  section  for  a  wing  surface  (in 
the  face  of  the  fact  that  no  successful  natural  or 
artifical  flier  uses  this  curve  or  setting — instead  of 


*  Since  the  foregoing  was  written,  the  author  has  been  placed  in 
a  position  to  announce  that  important  laws  of  aerodynamics  have  been 
fully  formulated  by  Professor  Montgomery,  and  have  been  put  to  com- 
plete and  most  remarkably  successful  tests  in  the  way  of  experimental 
verification  and  confirmation.  These  investigations,  a  part  of  which 
are  only  briefly  outlined  in  Pages  173  to  203,  inclusive,  will  in  the 
near  future  be  submitted  to  the  consideration  and  criticism  of  the 
world.  The  writer  confidently  predicts  that  they  will  not  only  amaze 
by  the  originality  and  completeness  of  the  researches  and  analyses 
involved,  but  will  also,  by  application  of  their  profound  principles, 
vastly  advance  the  science  of  aerial  navigation. 


FIGURE  75.- — Assembling  Wright  Wing  Frames.  The  complete  biplane  is  made  in  three 
portions,  the  center  section  slightly  overhanging  the  two  runners — between  which  stands 
the  man  at  the  left  of  the  view.  This  section  has  attached  at  each  end  a  section  like  that 
at  w — shown  at  the  moment  of  attachment.  Similar  sections  are  leaning  against  the  wall  at  v. 


FIGURE  76. — Aileron  Control  of  Lateral  Balance  in  Antoinette  Monoplane  by  manipulation 
of  the  two  hinged  tips  aa. 


FIGURE  77. — Bleriot  Monoplane  VIII.     The   feature  of  this   machine  was  the  control  of 
lateral  balance  by  the  pivoted  ailerons  aa. 


AEROPLANE  DETAILS  171 

coming  to  the  definite  conclusions  one  would  natu- 
rally expect  as  a  result  of  the  mathematical  method 
the  whole  question  is  characteristically  begged  in 
this  wise:  "We  cannot  follow  clearly  the  pressures 
and  motions  that  take  place  when  a  surface  travels 
obliquely  through  the  air — because  they  are  very 
involved",  as  if  there  could  be  any  possible  occasion 
for  a  technical  treatment  of  the  subject  that  should 
not  in  some  measure  dispel  the  confusion  that  sur- 
rounds it. 

FLAT  SECTIONS 

As  the  most  elementary  possible  conception  it 
is  quite  natural  that  many  among  the  earlier  and 
even  some  more  recent  aeroplane  experiments 
should  have  involved  the  use  of  flat  surfaces.  It  is 


FIGURE  42. — Pressure  on  Vertical  and  Inclined  Surfaces.  In  an  air 
current  of  25  miles  an  hour  the  surface  at  90°  receives  a  pressure  of  3.24 
pounds  to  the  square  foot,  while  the  surface  inclined  15°  from  the  direction 
of  the  current  receives  a  pressure  of  only  .33  pounds,  and  at  the  same  time 
affords  an  upward  lift  of  1.5  pounds. 

now  proved,  however,  that  such  surfaces  are  quite 
ineffective  as  Compared  with  curved  surfaces. 

Though  useless  for  sustention  in  any  prac- 
ticable aeroplane  construction,  except  by  wasting 
enormous  excesses  of  power,  a  flat  surface  well 
illustrates  a  basic  principle  of  sustention  by 
moving  an  inclined  surface  through  the  air,  as  is 
shown  in  Figure  42. 


172  VEHICLES  OF  THE  AIR 

CUBVED  SECTIONS 

The  sections  of  all  animal  wings  being  more  or 
less  curved  it  is  a  fairly  direct  conclusion  that 
there  are  important  reasons  behind  the  use  of  such 
formations — a  conclusion  that  becomes  stronger 
the  more  the  subject  is  studied. 

Arcs  of  Circles,  as  affording  curved  surfaces  of 
comparatively  simple  character,  were  the  first 
tried  by  early  dissenters  from  the  idea  of  flat  sur- 
faces. Their  use,  while  neither  as  scientific  nor  as 
successful  as  that  of  other  curves,  will  afford 
fair  results  under  certain  conditions,  but  far  more 
important  than  any  success  that  has  attended  their 
use  has  been  their  influence  in  suggesting  further 
deviations  from  preconceived  opinions.  For  ex- 
ample, Lilienthal  in  comparing  flat  with  curved 
surfaces  discovered  that  while  a  flat  surface  placed 
with  no  angle  of  incidence  in  a  horizontal  wind 


to  ^O.SZ  1C.  P. 

FIGURE  43. — Comparison  of  Plane  and  Arched  Surfaces  Without  Angle  of 
Incidence.  Lilienthal  found  that  while  the  lift  of  a  flat  surface  placed  as 
above  was  zero,  the  arc  of  a  circle  gave  a  lift  equal  to  52  percent  of  the 
pressure  upon  It  when  exposed  in  a  vertical  position  to  the  same  wind. 

afforded  no  lift,  as  would  be  expected,  a  circular 
arc  placed  in  the  same  position  gave  a  lift  equal 
to  52%  of  the  normal  pressure  on  the  same  surface 
held  vertically  in  the  same  wind!  This  phenome- 
non, which  is  illustrated  in  Figure  43,  is  to  be 
explained  only  by  there  being  an  effect  of  the  sur- 
face on  the  air  currents  in  advance  of  the  surface 
— realization  of  which  is  at  the  basis  of  all  sue- 


AEROPLANE  DETAILS  173 

cessf ul  work  in  aeronautics  and  all  correct  reason- 
ing upon  its  problems.  (See  Page  174). 

Parabolic  Surfaces,  with  minor  modifications 
(to  suit  certain  practical  exigencies)  into  approxi- 
mations of  other  of  the  conic  sections  and  other 
curves,  have  been  proved  experimentally  and  can 
be  demonstrated  mathematically  to  be  the  correct 
curves  for  wing  sections.  In  an  empirical  way 
this  was  first  deduced  by  Lilienthal  and  Phillips, 
while  exact  examination  proves  it  to  be  a  prin- 
ciple involved  in  the  curve  of  birds'  wings,  but  it 
has  remained  for  Montgomery  to  discover  the  laws 
involved.  These  are  deemed  of  such  importance 
that  the  following  popular  outline  of  the  prin- 
ciples involved  in  the  formation  of  wing  surfaces 
is  reprinted  as  the  most  valuable  and  practical 
material  available  for  the  student  of  the  subject.* 


"Although  the  subject  of  flight  has  been  a  constant 
and  universal  study,  we  find  that  some  of  the  phe- 
nomena are  still  involved  in  mystery,  while  many 
others  present  only  unexplained  anomalies.  This  of 
itself  would  suggest  the  question:  have  the  funda- 
mental principles  or  laws  been  formulated? 

"From  what  I  have  gleaned  from  the  writings  of 
the  various  students  I  believe  they  have  not — this  for 


*  This  paper,  which  was  revised  in  1907  for  presentation  to  the 
International  Aeronautical  Congress,  and  subsequently  published  in 
"Aeronautics,"  under  the  title  of  "Principles  Involved  in  the  Forma- 
tion of  Wing  Surfaces  and  the  Phenomenon  of  Soaring,"  is  an  amplifi- 
cation of  an  article  by  Professor  Montgomery,  entitled  "New  Prin- 
ciples in  Aerial  Flight, M  which  appeared  in  the  Scientific  American 
Supplement  of  November  25,  1905 — some  months  after  the  first  trials 
with  the  Montgomery  glider  in  California.  Much  earlier  than  this,  in 
1895,  substantially  the  same  material  was  submitted  by  Montgomery  to 
Octave  Chanute. 


174  VEHICLES  OF  THE  AIR 

the  reason  that  because  of  the  apparent  simplicity  of 
the  phenomena  we  are  tempted  to  take  too  much  for 
granted  and  have  been  misguided  in  our  trend  of 
thought.  My  own  studies  and  investigations  have 
forced  me  to  the  conclusion  that  in  flight  we  have  a 
special  and  unique  phenomenon,  which  for  its  compre- 
hension requires  something  more  than  the  simple  sug- 
gestions offered  by  the  study  of  surfaces  acted  upon 
by  the  moving  air,  just  as  the  action  of  the  gyroscope 
presents  special  phenomena  which  are  in  advance  of 
our  first  ideas  of  rotation. 

"  Having  this  view  of  the  subject  I  am  forced  to 
present  it  in  its  entirety,  as  I  have  been  unable  to  find 
any  researches  of  others  to  which  I  could  add  mine  as 
an  amplification,  and,  while  brevity  forbids  that  I 
should  enter  into  the  many  points  involved,  I  desire 
to  make  use  of  such  as  seem  to  constitute  a  direct 
and  complete  line  of  demonstration,  using  some  well 
known  phenomena  and  principles  and  developing  them 
in  the  lines  peculiar  to  this  problem. 

"At  the  Aeronautical  Congress  of  1893,  in  Chi- 
cago, it  was  my  privilege  to  call  attention  to  some 
phenomena  that  I  had  noted,  the  most  significant  of 
which  is  this :  A  current  of  air  approaching  an  inclined 
surface  is  deflected  far  in  advance  of  the  surface,  and 
approaching  it  in  a  gradually  increased  curve,  reaches 
it  at  a  very  abrupt  angle*  This  phenomenon  is  the 
basis  of  the  observations  and  studies  that  I  desire  to 
present  to  your  Congress. 

"In  the  idea  of  deriving  support  by  moving  an 
inclined  plane  through  the  air,  the  first  conception  is 

*  The  italics  are  ours.  This  exceedingly  early  recognition  by  Mont- 
gomery of  this  fundamentally-important  phenomenon,  still  little  ap- 
preciated by  many  modern  investigators,  is  alone  enough  to  establish 
its  discoverer  as  one  of  the  pioneers  of  successful  modern  aeronautics. 


FIGURE  78.- — Lejeune  Biplane,  with  forwardly-extended  ailerons  at  aaaa,  for  maintaining 
lateral  balance. 


FIGURE  79. — Front  View  of  Pischoff  and  Koecklin  Biplane,  with  aileron  controls  at  aa. 


FIGURE  80. — Side  View  of  Pischoff  &  Koecklin  Biplane,  showing  one  of  the  ailerons  very 
clearly  at  a.  The  ingenious  system  of  controlling  the  forward  elevator  hh  by  direct  con- 
nection of  the  steering  rod  e  to  the  steering  pillar  o  is  of  interest. 


FIGURE  81. — Aileron  Control  of  Farman  Biplane.     Tho  four  hinged  ailerons  are  shown  at 


AEROPLANE  DETAILS  175 

the  reaction  of  a  mass  meeting  or  impinging  upon  the 
inclined  surface,  in  consequence  of  which  the  surface 
and  the  mass  are  forced  in  opposite  directions.  This 
idea  would  be  complete  and  the  resulting  phenomena 
simple  and  reducible  to  well  known  formulae  if  the 
mass  acting  on  the  surface  were  a  solid,  but  in  the 
present  case  this  is  far  from  being  so,  as  the  mass  is 
an  almost  perfect  fluid,  and  the  resulting  phenomena 
are  varied  and  complicated  accordingly.  The  particles 
of  air  coming  in  contact  with  the  surface  are  deflected 
as  a  solid  mass  would  be,  but  in  being  driven  from 
their  course  they  are  forced  against  other  exterior 
particles,  which  while  deflecting  the  course  of  the  first 
particles  are  themselves  disturbed. 

"The  questions  presented  by  these  considerations 
are :  first,  what  is  the  nature  of  the  movements  of  the 
particles  due  to  these  deflections  and  disturbances; 
second,  what  form  of  surface  is  best  suited  for  pro- 
ducing the  original  deflection,  and  then  meeting  the 
new  conditions  arising  from  the  disturbance  in  the 
surrounding  air;  and,  third,  what  is  the  mechanical 
effect  of  the  particles  thus  disturbed  or  thrown  into 
motion.  In  the  study  of  the  first  two  questions,  obser- 
vation of  the  movements  of  a  fluid  is  the  safest  guide. 
For  this  observation  we  may  use  a  gas  or  a  liquid, 
as  both,  being  fluid,  show  the  same  phenomena  and 
reveal  the  same  laws;  the  only  important  difference 
being,  that  owing  to  the  limited  viscosity  of  a  gas,  its 
movements  are  more  perfect  and  rapid  than  those  of 
a  liquid,  whose  viscosity  hinders  the  perefectly  free 
movement  of  the  particles.  But  owing  to  the  ease 
with  which  the  experiments  may  be  performed  and 
the  movements  detected,  the  use  of  a  liquid  offers 
many  advantages.  For  the  purpose  of  study,  I  used 


176  VEHICLES  OF  THE  AIR 

a  broad  sheet  of  water  (preferably  distilled,  as  a 
slight  surface  tension  in  ordinary  water  prevents 
certain  delicate  movements  being  revealed)  which  by 
suitable  means  can  be  set  in  motion,  giving  a  perfectly 
even  stream  whose  velocity  is  regulated  at  will,  to 
make  manifest  the  various  phenomena. 

"The  first  phenomena  to  be  noted  is  when  the 
water  is  at  rest.  If  a  tube  be  placed  close  to  and 
parallel  with  the  surface,  ^ 

and  a  quick  blast  of  air  f       ^ 

is  forced  through  it,  two  \          j 

opposite   whirls    are  ^ ^  *• 

formed,    which    advance  S  ^\ 

over  the  surface  as  they  ' 

increase   in   size,    as   in  \^  ^/ 

Figure    44.      These    are  FlGURB  44 

made  manifest  by  very 

light  chaff  sprinkled  on  the  surface.  In  passing,  I 
may  note  the  difference  between  the  action  in  water 
and  in  air.  If  a  similar  puff  be  made  in  air,  by  which 
vortex  rings  are  produced,  we  notice  that  the  elements 
of  rotation  forming  a  section  of  the  ring  are  much 
smaller  and  more  rapid  than  these  rotations  shown 
in  water. 

"But  if  a  small  flat  surface  b,  Figure  45,  be  placed 

in  the  water  and  a  steady 
jet  forced  through  the 
tube  a,  two  whirls  are  pro- 
duced  and  maintained  in 
front  of  the  surface  and 
two  in  the  rear,  while 

rIGURE    45 

some  of  the  rotating  ele 

ments  of  those  in  the  rear  conflict  and  then  blend  to 
form  a  stream  c. 

"If  the  surface  be  placed  at  a  small  angle  to  the 


AEROPLANE  DETAILS 


177 


jet,  as  in  Figure  46,  there  is  a  breaking  up  of  the 
system  of  rotations,  but  that  corresponding  to  d, 
Figure  45,  is  developed  and  predominates.  The 
impulse  sent  from  the  jet  over  the  surface  simply 
reveals  the  tendency  to  rotation  when  a  stream 
impinges  upon  a  surface.  This  tendency  may  or  may 
not  appear  as  an  actual  rotation  according  to  circum- 
stances, as  the  following 
will  show.  If  a  plane  be 
placed  in  shallow  water, 
its  lower  edge  resting  on 
the  bottom,  and  moved 

gently  in  a  direction  perpendicular  to  its  surface,  then 
stopped;  four  rotations,  corresponding  to  those  of 
Figure  45,  will  appear,  which  move  away  in  the  direc- 
tion c  c  c  ct  Figure  47.  Again  *_ 
if  this  plane  be  moved  at  an 
angle  (about  45°  seems  best) 
in  Figure  48,  and  then 


as     n        gure        ,    an         en 
stopped,  the  two  rotations  cor-    ( 


c 


FIOUBB  47 


stopped,  the  two  rotations  cor- 
responding to  e  and  g,  Figures 
45   and   47,   will  have   disap- 
peared and  those  correspond- 
ing to  /  and  d  will  remain.    It  will  be  noted  that  these 
two  have  the  same  direction  of  rotation,  while  at  the 
same  time  there  is  an  incipient  rotation  in  the  water 
4    /-^N  as  indicated  by  the  small  ar- 

*    V    f     y      \  r°WS    ^* 

\      *}     YjKtf       "^  a^  ^ne  verv  fostant  of 
*       — ^-    stoppage  the  plane  be  quickly 
lifted   from    the   water,    the 
two  rotations,  /  and  df  will 
immediately  blend  and  form 
themselves    into    one    large 
rotation,    as   is   very   clearly   shown   in   Figure   49. 


FIGURE   48 


178 


VEHICLES  OF  TEE  AIR 


FIGURE  49 


"From  these  experiments  we  see  that  a  surface 
moving  a  fluid  has  a  tendency  to  build  up  rotations, 
which  under  certain  circumstances  will  blend  into  one, 
this  being  retrograde  as  shown  in  the  last  experiment, 
with  the  ascending  element  of  rotation  in  advance  of 

the  surface.  Further  tests  in 
moving  water  will  reveal  this 
more  completely  (with  other 
interesting  phenomena  appli- 
cable to  questions  of  equi- 
librium). 

"A  surface  a,  Figure  50,  is 
placed  in  a  gentle  stream  s  and  immediately  whirls  will 
be  noted  in  its  rear,  which  on  examination  are  seen  to 
have  a  synchronous  movement 
whose  time  is  dependent  on  the 
velocity  of  the  stream  and  the 
size  of  the  surface.  At  one  — 
instant  the  whirl  d  is  devel- 
oped so  as  to  occupy  the  whole 
space,  while  the  whirl  e  is  sup- 
pressed to  a  minimum.  At  this  instant  d  moves  in  the 
direction  c,  while  e  develops,  and  another  d  exists  as  a 


FIGURE  50 


» 

-s 

( 

^ 

(  e  ) 
^s 

'/^—i 

"    I    e 

\ 
N 

V- 

\^ 

FIGURE  51 

* 

miniature,  as  shown  in  Figure  51.    Between  these  alter- 
nately escaping  whirls  there  is  a  wave  line,  shown  at 


AEROPLANE  DETAILS  179 

w,  Figure  51,  suggestive  of  the  waving  of  a  flag  (the 
latter  phenomenon  being  definitely  due  to  the  existence 
of  such  whirls) ;  while  at  the  same  time,  on  the  surface 
of  the  water  in  front  of  the  plane  delicate  lines  appear, 
which  swing  from  side  to  side  with  the  movements  of 
the  whirls  in  the  rear.  These  lines  are  not  ordinary 
wave  lines,  but  sharp  distinct  lines  of  division  between 
the  movements,  etc.,  of  the  fluid  immediately  related 
to  or  influenced  by  the  deflecting  surface,  and  the  rest 
of  the  fluid  mass  approaching  it,  while  the  whirls  in 
the  rear  indicate  a  similar  division.  These  and  other 

phenomena  indicate 
that,  though  there  is  a 
general  movement  in 
the  fluid  produced  by  a 
deflecting  surface,  there 

FIGURE  52  °  ; 

is  a  distinction  between 

that  immediately  related  to  the  surface  and  that  which 
is  further  removed. 

"When  the  plane  a  is  placed  at  an  angle  with  the 
stream,  as  in  Figure  52,  the  whirls  continue  to  appear 
and  alternately  escape,  d  being  more  pronounced  and 
powerful  than  e,  while  the  stream  at  c  rises  in  front 
of  the  plane  and  that  at  w  descends.  If  the  planes  in 
these  two  tests  are  pivoted  so  as  to  be  capable  of  a 
free  movement,  they  take  up  a  slight  swinging  or 
rocking  motion,  responsive  to  the  movements  of  the 
whirls.  This  movement  is  much  more  pronounced  if 
similar  tests  be  made  by  moving  corresponding  sur- 
faces through  the  air. 

"Up  to  this  point  we  have  seen  enough  to  indi- 
cate :  first,  that  an  impulse  in  a  fluid  tends  to  set  up  a 
series  of  rotations ;  and  second,  that  a  surface  inclined 
to  the  impulse  tends  to  suppress  some  of  these  rota- 


180  VEHICLES  OF  THE  AIR 

tions  while  augmenting  others,  and  finally  to  blend 
all  into  one.  An  analysis  of  these  points  must  be 
omitted  for  brevity's  sake.  However,  this  element  of 
rotation  will  appear  again  in  speaking  of  the  proper 
form  and  adjustment  of  surfaces. 

"In  determining  the  proper  form  of  surface,  the 
first  suggestions  are  derived  from  the  conception  of  a 
body  projected  in  a  straight  line  but  deflected  from 
its  course  by  a  constant  force  acting  at  right  angles 
— as  a  mass  projected  horizontally  and  pulled  down 
by  gravity,  thus  describing  a  semi-parabola,  according 
to  well  known  laws. 

"In  Figure  53  let  a  b  represent  the  direction  and 
distance  a  mass  m,  projected  horizontally,  would  pass 

in  two  instants  of  time, 
a  e  and  e  b  representing 
equal  times.  But  under 
the  action  of  gravity, 
the  mass  will  describe 

53  the  curve  a  \ d'     Dr°P 

the    perpendicular     e  h 

to  the  curve;  then  the  point  h  will  mark  its  position 
at  the  end  of  the  first  instant,  while  d  is  its  position 
at  the  end  of  the  second.  Then,  as  the  work  per- 
formed by  gravity  during  the  two  periods  of  time  is 
equal,  that  performed  on  a  h  equals  that  on  h  d.  But 
as  the  converse  of  this  is  true,  if  a  h  d  be  a  curve  and 
a  mass  m  is  driven  along  its  surface  by  a  force  /, 
parallel  with  a  b,  its  reaction  against  the  curve  will 
exert  pressures  perpendicular  to  a  b,  which  are  equal 
on  the  two  branches  a  h  and  Ji  d.  "While  this  idea 
affords  an  elementary  conception,  we  find  it  does  not 
fully  satisfy  the  requirements  of  a  moving  fluid  mass, 
and  applies  only  to  those  particles  in  contact  with  the 


AEROPLANE  DETAILS 


181 


surface.    Hence  we  must  look  to  some  other  analysis 
for  a  full  conception.* 

"In  a  study  of  the  parabola,  we  find  it  has  an 
intimate  relation  to  the  tangent  at  its  vertex  and  the 
circumference  of  an  osculatory 
contiguous  circle  whose  center 
is  at  its  focus,  as  shown  in  Fig- 
ure 54.  In  this  a  b  is  the  di- 
rectrix, I  m  the  tangent,  and  c 
the  focus.  In  the  evolution  of 
the  parabola,  fg=cg, Jc h=c  h, 
etc.  Subtracting  the  distance 
a  I,  between  the  directrix  and 
the  tangent,  from  /  g,  k  h,  etc., 
and  the  radii  of  the  circle  from 
c  g,  c  h,  etc.,  the  differences  are 

equal,  that  is,  the  perpendicular  distances  from  the 
circle  are  equal  to  those  from  the  tangent.  A  further 
study  of  this  development  shows  that  all  these  lines, 
/  9 9  c  9>  etc.,  form  equal  angles  with  the  tangents  to  the 
*  curve  at  the  points  of  inter- 

\c  section.   From  these  two  con- 

siderations we  see  that  equal 
impulses  from  the  tangent  I  m 
and  the  circumference  of  the 
circle  will  meet  at  the  curve, 
producing  resultants  in  the 
direction  of  the  tangents  at  these  points.  And  finally, 


FIGURE  54 


FIGURE  55 


*  To  students  who  are  able  to  follow  them,  the  reasoning  and  the 
analyses  from  this  point  to  the  end  of  Professor  Montgomery's  paper 
are  commended  as  worthy  of  the  profoundest  attention  and  consideration. 
The  time  is  certain  to  come  when  the  clear  logic  and  brilliancy  of  these 
remarkable  investigations  and  conclusions,  taken  in  conjunction  with 
their  wonderful  experimental  verification  in  California  in  1905  (see 
Page  138),  will  rank  their  author  not  merely  with  present-day  aviators, 
but  with  the  world's  greatest  physicists  and  mathematicians. 


182  VEHICLES  OF  THE  AIR 

according  to  a  well  known  property  of  the  curve,  all 
impulses  from  the  center  will  be  reflected  from  a  par- 
abolic surface  in  parallel  lines  (as  j  j),  and,  vice  versa, 
all  parallel  impulses  (as  j  j)  reaching  the  surface  will 
be  reflected  to  the  focus  c. 

"  Before  making  application  of  these  properties,  I 
must  call  attention  to  a  phenomenon  of  jets  or  streams. 
If  two  jets  impinge  on  one  another,  as  shown  at  a  and 
b,  Figure  55,  the  particles  will  escape  at  the  point  of 
impact  in  lateral  movements  c  c.  If  the  streams  are 
equal,  the  point  of  impact  well  remain  fixed ;  but  if  they 
are  not,  it  will  be  driven  towards  the  weaker  jet. 

"The  application  of  these  various  elements  is 
shown  in  Figure  56,  in  which  a  h  d  is  a  parabolic  sur- 
face placed  in  a  fluid  and  s  is  a  jet  fixed  in  the  line  a  b. 
When  an  impulse  from  this  jet  impinges  on  the  surface 
it  will  develop  pressures  against  the  surface  as  shown 
in  Figure  53,  but  as  it  continually  moves  away  from 
the  tangent  line  a  &  it  produces  pressures  on  the  adja- 
cent fluid,  as  shown  by  the  arrow  /.  And,  further,  as 
it  moves  along  the  curve,  meeting  the  reaction  of  the 
fluid  as  shown  at  o,  it  produces  the  phenomena  shown 
j  in  Figure  55.  And  as  the  direc- 
tion of  impact  is  parallel  with 
the  tangent  at  this  point,  one 
element  of  the  resulting  lateral 
pressure,  is  against  and  normal 
to  the  curve;  while  the  oppo- 
site element  is  towards  the 
fluid  mass,  and  in  the  direction 
'FIGURE  56  the  normal  m  n.  But  an  analy- 

sis of  the  normal  shows  it  is 

composed  of  two  equal  elements,  one,  m  c,  pointing  to 
the  center  c,  and  the  other,  m  j,  perpendicular  to  the 


AEROPLANE  DETAILS  183 

line  a  b.  As  this  impact  of  the  stream  and  reaction  of 
the  disturbed  fluid  takes  place  along  the  entire  surface, 
producing  a  normal  pressure  at  every  point,  there  is  a 
diversity  of  pressures  in  the  fluid  mass,  which  diversity 
is  harmonized  by  the  analysis  given;  all  the  elements 
represented  by  m  c  going  to  the  center  c  to  build  up  a 
center  of  pressure,  while  the  elements  represented  by 
m  j  develop  parallel  pressures  against  the  fluid.  These 
pressures  being  parallel  with  those  represented  by  / 
combine  with  the  latter  to  produce  a  compound  effect — 
first,  they  impart  to  the  adjacent  mass  the  movements 
p  p  p,  and  this  movement  sets  up  a  rotation  around  the 
center  c;  and,  second,  the  reaction  of  the  disturbed  mass 
against  the  impulses  /  and  j  is  transmitted  as  an  im- 
pulse back  to  the  surface,  and  is  reflected  to  the  center 
cy  thus  increasing  the  compression  at  this  point.  As 
might  be  surmised,  the  reflected  impulses  to  the  center 
c  would  have  a  tendency  to  drive  it  out  of  position,  but 
the  impulse  s  (as  an  element  building  up  this  rotation), 
is  an  opposing  force,  keeping  it  in  place.  Owing  to  the 
concentration  of  the  various  lines  of  force,  and  the  re- 
straining influences,  and  because  of  the  rotation,  the 
point  c  becomes  a  center  of  pressure  from  which  there 
are  constant  radiating  impulses,  which  reaching  the 
curve  are  reflected  from  its  surface  in  lines  parallel 
with  the  first  impulses.  But,  as  a  radiating  center 
sends  out  equal  impulses  in  equal  angles,  there  is  a 
new  distribution  of  pressure  on  the  curve  because  of 
these  radiated  impulses.  An  inspection  of  Figure  54 
will  show  that  the  angle  i  c  e  =  e  c  d.  Hence,  the  im- 
pulses falling  on  I  g  equal  those  falling  on  g  d.  The 
point  g  then  becomes  the  center  of  pressure  on  the 
curve  due  to  the  radiated  impulses  from  c,  while  Ji  is 
that  due  to  the  parallel  impulses  from  the  first  reac- 


184  VEHICLES  OF  THE  AIR 

tions,  /,  Figure  56,  of  the  moving  particles  against  the 
curve.  But  between  the  points  g  and  h  there  snould 
be  another  central  point  of  pressures  due  to  the  ele- 
ments m  n.  The  reason  for  this  will  appear  in  the  fol- 
lowing consideration.  Suppose  we  have  a  number  of 
elastic  particles  in  a  straight  line,  and  a  constant  force 
acts  on  the  first;  each  particle  successively  will  react 
against  the  force,  thereby  building  up  a  gradually 
increasing  pressure,  till  the  last  is  set  in  motion. 
And  owing  to  these  successive  increments  of  reaction 
against  the  force,  the  pressure  will  be  least  at  the  last 
particle,  gradually  increasing  in  an  arithmetical  pro- 
gression to  the  first.  From  this  it  would  appear,  that 
the  elements  m  n  should  increase  in  intensity  from  d 
to  a,  thereby  causing  the  central  point  of  pressure, 
from  these  elements,  to  be  located  near  the  front  edge 
(approximately  one-third  the  total  distance). 

"  Another  conclusion  from  this  principle  of  succes- 
sive reactions  is,  the  greater  the  number  of  particles 
in  series  the  more  intense  should  be  the  pressure,  and 
as  a  general  result  of  this  the  intensity  of  pressure  on 
a  surface  should  increase  with  its  dimensions.  And  in 
the  special  application  to  wing  surface  in  gliding  move- 
ment (where  the  escape  at  the  ends  is  cut  off  by  the 
length  of  the  wings),  the  intensity  should  be  propor- 
tional to  the  width.* 

"This  principle  seems  to  receive  confirmation  in 
the  following  experiment.  If  a  plane  be  placed  in  a 
constant  stream,  perpendicular  to  its  surface,  the  ele- 
vation of  the  water  will  increase  from  its  edges  to  its 
center.  But  if  the  plane  be  doubled  in  width,  the  eleva- 


*  This  is  undoubtedly  the  law  underlying  the  well-recognized  decrease 
in  proportion  of  area  to  weight,  as  the  creatures  become  larger,  in 
nature's  flying  machines. — [ 


AEROPLANE  DETAILS 


185 


tion  at  the  center  will  be  much  greater  than  in  the  first 
instance,  and  as  the  elevation  may  be  taken  as  an 
indication  of  the  pressure,  the  conclusion  is  obvious. 

"In  an  experiment  illustrated  in  Figure  57  some 
of  the  phenomena  mentioned  are  shown.  In  this  a  b 
and  a  d  are  two  surfaces,  corresponding  to  a  h  d,  Fig- 
ure 56,  placed  in  shallow  water,  and  j  is  a  jet  of  air 
near  and  parallel  with  the 
surface.  The  jet  sets  up 
a  stream  on  the  surface, 
which  is  cut  by  the  point 
a  and  flows  along  the  j 
curves  as  shown  at  h  and 
i.  In  flowing  along,  these 
streams,  h  and  i,  set  up 
movements,  as  shown  by 
the  small  arrows,  which 
pass  into  rotations  around 

the  points  c  f.  Particles  of  chaff  on  the  surface  reveal 
these  movements,  while  pins  fixed  at  the  foci  of  the 
parabolic  curves,  and  extending  above  the  surface, 

assist  in  observation. 

"If  the  planes  shown  in 
the  last  experiment  are 
placed  in  a  stream  s,  Fig- 
ure 58,  the  same  develop- 


ment  of  pressures  takes 
place    but    the    complete 
rotations   are  hidden  be- 
cause of  the  general  move- 
ment,   though    they    sub- 
stantially exist  in  a  gen- 
eral wave  line.    In  this  system,  there  are  three  general 
elements  of  action  and  reaction;  first  and  second  are 


FlGUBE    58 


186  VEHICLES  OF  THE  AIR 

h  and  i,  which  mutually  hold  one  another  in  balance, 
and  act  reciprocally  in  building  up  and  maintaining 
the  various  movements  and  pressures;  and  the  third, 
these  combined  reacting  on  the  exterior  stream,  ac- 
cord to  the  statements  in  the  discussion  of  Figures  50 
and  51.  Should  one  of  the  elements  h,  for  instance, 
be  removed  by  taking  away  the  curve  a  d,  the  develop- 
ment would  be  destroyed  and  there  would  be  an  escape 
from  i  towards  the  side  h.  And  in  order  to  re-estab- 
lish the  pressures  on  the  curve  a  b  there  must  be  a 
readjustment  by  which  the  necessary  element  is  de- 
rived from  the  stream.  An  inspection  of  the  figures 
shows  that  the  rotary  tendencies  around  /  press  upon 
those  of  c  and  also  on  the  rear  of  the  curve  a  b.  Then 
if  we  draw  a  tangent  of  this  circle  /  to  the  point  b,  and 
so  place  the  curve  that  the  stream  comes  from  the 
point  m,  we  find  the  desired  adjustment,  though  the 
pressures  on  the  curve  are  derived  from  modifications 
of  the  ideal  movements. 

"On  placing  the  curve  a  b  so  that  the  stream  ap- 
proaches in  the  direction  m  b,  Figure  59,  we  test  the 
d  adjustment  as  follows: 

Fine  sand  scattered  at 
%  on  ^e  k°tt°m  b    its 


59 

novements  will  indicate 

that  the  approaching  stream  is  cut  by  the  point  or  edge 
a.  But  if  this  point  be  lowered,  there  will  be  a  pressure 
on  the  upper  surface,  causing  a  whirl  /.  Whereas,  if  it 
be  elevated  a  reverse  whirl,  c,  is  produced,  as  shown  in 
the  illustration. 

"In  Figure  60  we  have  a  good  illustration  of  the 
complete  system  of  movements  in  this  adjustment. 
The  stream  5  gradually  rises  and  is  cut  by  the  edge  b; 
the  portion  flowing  below  the  curve  slows  up  and  is 


AEROPLANE  DETAILS 


187 


more  or  less  ill-defined  in  its  movement.  But,  pressing 
against  the  curve,  it  causes  the  water  level  to  rise  and 
passes  out  as  shown  by  the  arrows  g.  Near  the  sur- 
face of  the  curve  there  are  jerky  movements  as  shown 
at  c  c  c.  Above  the  surface,  the  current  sweeps  around 
a,  leaving  a  deep  depression,  but  turns  and  descends 


FIGURE  60 

against  the  rear  upper  surface,  and,  conflicting  with 
the  currents  coming  around  the  rear  point  e,  produces 
a  violent  disturbance.  Some  of  the  current  around  e 
takes  the  direction  n  but  terminates  in  the  whirl  m. 
In  the  rear  the  various  movements  combine  and  form 
a  displaced  current,  traveling  in  the  direction  /,  par- 
allel with  the  original  stream.  Owing  to  the  pressure 
exerted  by  the  descending  current  on  the  upper  rear 
surface,  the  effectiveness  of  that  on  the  under  surface 
is  reduced.  An  inspection  shows  the  height  of  water 
from  e  to  h  to  be  only  a  little  more  than  that  from  e 


188  VEHICLES  OF  THE  AIR 

to  m,  while,  owing  to  the  deep  depression  at  a  and  the 
elevation  from  b  to  h,  the  greatest  effective  pressure 
is  located  in  this  region.  The  general  movement  of  the 
current  forms  a  wave  line,  this  being  a  resultant  of 
rotary  movements  and  the  rectilinear  movement  of  the 
stream. 

"But  the  complete  rotation,  indicated  by  the  circle 
of  arrows,  gives  a  positive  demonstration,  and  may 
be  produced  as  follows : 

"Let  the  velocity  of  the  stream  be  gradually  de- 
creased till  a  reverse  current  takes  place  on  the  surface. 
This  reverse  current  will  carry  all  the  floating  particles 
towards  upper  end  of  the  stream.  In  this  movement, 
these  floating  particles  serve  as  an  indicator  for  any 
general  tendencies  in  the  water,  and,  on  reaching  the 
region  of  the  curved  surface,  take  up  the  indicated 
rotation,  continuing  to  rotate  around  the  surface  with 
perfect  regularity  as  long  as  the  stream  continues; 
meanwhile  the  suspended  particles  of  chaff  reveal  the 
varied  movements  within  the  stream.  In  passing,  I 
must  state  it  is  not  easy  to  produce  this  surface  whirl. 
The  movement  of  the  water  must  be  perfectly  regular 
and  under  perfect  control  as  to  velocity.  There  must 
be  no  irregularities  in  the  channel  and  the  water  must 
be  as  free  as  possible  from  viscosity  and  any  surface 
film,  rain  water  being  the  only  kind  I  have  succeeded 
with. 

"While  this  seems  to  be  the  ideal  of  the  form  and 
position  of  a  surface  for  receiving  fluid  impulses  and 
developing  the  proper  reactions,  there  are  certain 
modifications  to  be  introduced  in  practice  as  will  ap- 
pear from  the  following: 

"It  will  be  noticed  in  these  demonstrations  that 
the  free  movements  of  the  water  are  referred  to  the 


AEROPLANE  DETAILS  189 

front  and  rear  edges,  there  being  no  escape  around  the 
edges  at  the  bottom  or  the  surface  of  the  stream.  But 
if  we  take  a  curved  surface  narrow  enough  to  be  sub- 
merged, part  of  the  fluid  will  escape  over  the  upper 
edge,  and  the  reactions  necessary  to  produce  the  rising 
current  in  advance  of  the  plane  are  only  partially 
developed.  Hence  to  have  the  front  edge  cut  the  cur- 
rent, it  must  be  elevated.  This  required  elevation  of 
the  front  edge  increases  as  the  surface  is  more  com- 
pletely submerged,  as  the  escape  of  the  water  over 
the  upper  edge  is  thereby  increased.  But  if  portions 
of  the  front  edge,  as  shown  at  a  b  c  d,  etc.,  Figure  61, 

be  cut  off,  to  allow  for  the 
deficiency  in  the  rising  cur- 

rent»   tne   front    e<*ge   of   tne 

curve  may  be  lowered  so  that 

the  remaining  portion  of  the  curve  may  assume  its 
proper  position.  The  application  of  this  is  readily 
apparent  in  the  wings  of  a  soaring  bird.  Towards  the 
center,  near  the  body,  the  curvature  is  at  its  fullest 
development.  But  near  the  outer  extremities,  where 
the  air  partially  escapes  around  the  ends,  the  sharp 
front  curvature  disappears,  the  wing  surface  becoming 
less  curved  and  more  narrow — a  fact  that  has  been 
noted  by  many  investigators. 

"Here  I  must  call  attention  to  an  important  ele- 
ment. In  discussing  Figures  54,  55,  and  56  I  pointed  out 
the  positions  of  the  centers  of  pressures,  and  in  Figure 
62  we  find  the  application.  Let  e  b  be  the  horizontal, 
and  also  the  direction  of  movement  of  the  curve  a  b,  in 
its  proper  position.  From  the  construction,  we  see  that 
the  center  of  pressures  due  to  the  direct  reaction  of  the 
moving  particles  is  at  /  while  that  due  to  the  pressure 
emanating  from  the  center  c  is  at  g.  If  we  draw  a 


190 


VEHICLES  OF  THE  AIR 


normal  from  the  point  /,  its  inclination  is  against  the 
direction  of  motion,  e  b.  But  one  drawn  from  g  in- 
clines with  it,  or  for- 
ward. The  resultant  of 
these  two  pressures  is 
~*  indicated  by  h,  and  the 
normal  to  the  tangent  at 
this  point  shows  a  slight 
forward  pressure.  From 
the  study  of  Figure  56 
we  find  that  there  is  a 
third  element  of  pres- 
sure, m  n,  whose  intensity  is  greatest  towards  the 
front.  This  again  changes  the  location  of  the  center 
of  pressure,  placing  it  in  advance  of  the  point  h.  And 
as  the  normal  at  this  point  inclines  forward,  there 
should  be  a  perceptible  forward  pressure  developed, 
a  phenomenon  I  have  observed  when  testing  my  aero- 
planes, and  one  which  I  believe  has  been  observed  by 
others.* 

"These  conclusions  regarding  the  location  of  the 
center  of  pressure  seem  to  be  confirmed  by  observa- 
tions made  when  I  first  entered  this  study.  Taking 
specimens  of  large  birds,  eagles,  pelicans,  buzzards, 
etc.,  newly  killed,  I  braced  their  wings  in  the  normal 
position  of  soaring.  I  then  balanced  the  body  by  thrust- 
ing sharp  points  into  it,  immediately  under  the  wings, 
(frequent  corrections  having  been  made  to  adjust  the 
bracing  so  as  not  to  introduce  errors  into  balancing), 
and  I  found  the  center  of  gravity  under  a  point  in  the 
wing  approximately  corresponding  with  the  point  I 
have  indicated  as  being  the  center  of  pressure. 

*  This  is  the  so-called  ' '  tangential ' '    noted  by  Lilienthal,  and  con- 
firmed by  the  Wrights  and  others. — [Eo.j 


AEROPLANE  DETAILS  191 

"Before  leaving  this  part  of  the  subject  I  must  call 
attention  to  two  important  elements — first,  from  a 
study  of  Figures  59  and  60  it  is  seen  that  it  is  the 
reaction  within,  or  under,  the  curve  that  causes  the 
ascending  current  in  advance  of  the  curve,  hence, 
should  there  be  an  object  within  this  space,  causing  a 
resistance  to  the  fluid  movement,  it  by  reaction  will 
further  increase  this  rising  current,  and  as  this  is  in- 
creased the  front  edge  may  be  lowered  still  more,  and 
thereby  the  element  of  pressure  on  the  forward  sur- 
face augmented,  which  will  partially  compensate  for 
the  resistance  due  to  the  object;  second,  in  the  use  of 
two  surfaces,  one  in  advance  of  the  other,  the  line  of 
development  is  suggested  in  Figure  59.  Suppose  this 
surface  be  divided  at  d  and  the  sections  moved  apart, 
the  intervening  space  gives  to  each  part  an  individual- 
ity, but  their  mutual  reactions  give  them  an  interrela- 
tion. Hence  in  the  practical  use  of  such  surfaces  the 
curvature  of  that  forward  should  be  more  pronounced, 
and  its  inclination  greater  than  that  in  the  rear.  How- 
ever, without  a  proper  understanding  how  to  deter- 
mine these  elements  dangerous  mistakes  might  be 
made.* 

"Having  pointed  out  what  seem  to  be  the  funda- 
mental principles  in  the  formation  and  adjustment  of 
a  gliding  or  soaring  surface,  I  now  place  the  whole 
idea  in  a  single  expression,  as  a  stepping  stone  to  the 
consideration  of  mechanical  principles  relative  to  the 
problem  of  the  energy  involved. 


*  Definite  laws  have  been  found  to  exist  in  accordance  with  which 
the  relation  between  the  focal  length  and  the  chord  length  of  the 
parabola  varies  in  accordance  with  the  size  of  the  machine  and  with 
the  sustention  per  unit  of  area.  At  the  present  time  the  writer  is 
not  at  liberty  to  make  public  this  data,  but  hopes  to  be  in  a  position  to 
do  so  in  the  near  future. 


192  VEHICLES  OF  THE  AIR 

"Conceive  a  long  narrow  surface,  such  as  a  bird's 
wings  in  a  horizontal  position,  having  no  formed  mo- 
tion, but  being  pulled  down  by  gravity.  In  descending 
through  the  air  this  surface  sets  up  two  whirls  around 
its  edges,  and  we  readily  perceive  that  the  work  of 
gravity  in  pulling  the  surface  down  is  divided  between 
the  descending  surface  and  the  whirls  escaping  around 
its  edges.  Now,  suppose  the  surface  be  given  a  hori- 
zontal movement  of  such  velocity  that  the  complete 
system  of  movements  shown  in  Figure  60  is  built  up ; 
then  these  opposite  whirls  being  blended  into  one  rota- 
tion, having  its  ascending  elements  in  advance  of  the 
surface,  the  work  of  gravity  impressed  upon  the  air 
comes  back  to  the  surface,  giving  it  an  upward  impulse. 

"Now  let  us  inquire  what  is  the  significance  of  this 
operation,  relative  to  the  question  of  energy.  This 
point  is  well  worthy  of  the  sincerest  inquiry,  for  who 
has  not  been  enchanted  and  mystified  by  the  beautiful 
movement  of  the  soaring  bird?  And  who  has  not  asked 
the  question,  over  and  over  again,  whence  does  it  derive 
the  power  to  perform  such  feats,  so  much  at  variance 
with  other  phenomena  and  our  ideas  of  motion  ! 

"Having  passed  through  the  ordeal  of  these  per- 
plexing questions,  and  been  forced  to  their  solution  by 
going  back  to  the  infancy  of  mechanics,  I  am  compelled 
to  state  that  some  of  the  elementary  questions,  as  they 
appear  in  our  text  books,  have  not  been  developed  as 
completely  as  they  should  have  been,  and  thus  the 
minds  of  even  the  best  students  have  been  left  with 
some  erroneous  conclusions,  attributable  directly  to  a 
too  restricted  investigation. 


"In  entering  into  this  question  let  me  suggest  that 
we  abstract  our  minds  as  far  as  possible  from  all 


AEROPLANE  DETAILS  193 

knowledge  and  conclusions  on  the  subject,  so  as  to 
follow  the  building  up  of  the  demonstrations  without 
prejudicing  them  by  ideas  that  we  possess,  or  which 
must  in  their  natural  order  come  later.  As  may  be 
inferred  from  the  preceding  we  shall  simply  go  back  to 
the  most  elementary  principles,  and  expand  them,  em- 
phasizing such  points  as  relate  to  the  question." 

FORCE  AND  MOTION 

"A  force  acting  upon  a  movable  mass  imparts  to 
it  a  velocity  which  is  a  product  of  the  force  multiplied 
by  the  time  of  action ;  v  =  ft. 

'  '  The  force  may  be  a  pure  force,  as  gravity,  it  may 
be  the  pressure  of  a  compressed  elastic  body,  or  it  may 
be  the  impact  of  a  moving  mass.  Regarding  the  forces 
derived  from  a  moving  mass  it  may  be  stated  that 
when  there  is  a  series  of  impacts,  the  element  of  time 
is  composed  of  the  duration  of  each  impact  multiplied 
by  the  number. 

"From  a  confusion  of  ideas  on  this  subject  erro- 
neous conclusions  sometimes  arise.  A  force  is  simply 
considered  a  force  in  a  general  way,  and  must  produce 
so  much  motion  and  no  more,  the  element  of  time  and 
the  factors  that  determine  it  being  entirely  lost  sight 

of.    Experiments  illustrated 
in  Figure  63  will  be  instruc- 
tive on  these  points.    A  and 
,     B  in  this  illustration,  are  two 
^x'        masses  fastened  to  rods  and 
H  supported  by  the  pivots  /  /. 

FIGURE  63  Between  them  is  the  spring 

c.     In  the  first  experiment, 

let  A  and  B  be  equal.  If  the  compressed  spring  be  re- 
leased, it  will  drive  the  two  masses  apart,  A  reaching 


194  VEHICLES  OF  THE  AIR 

the  point  d,  but  in  a  second  experiment  let  B  be  greater 
than  in  the  first,  A  remaining  the  same ;  then  when  the 
compressed  spring  is  liberated,  the  mass  A  is  forced 
to  a  higher  point,  e,  owing  to  a  greater  velocity  being 
developed  through  the  time  of  action  being  prolonged 
by  the  greater  inertia  of  the  larger  mass  B.  A  full  and 
clear  conception  of  the  formula  v  =  ft,  and  a  realiza- 
tion of  the  fact  that  the  masses  operated  upon  are  im- 
portant elements  in  determining  the  time,  are  neces- 
sary to  an  understanding  of  the  present  problem. '  * 

MOMENTUM 

"When  a  mass  is  in  motion  we  have  not  only  the 
question  of  velocity,  but  also  that  of  quantity  of  mo- 
tion, or  momentum,  expressed  by  the  formula  m  v.  A 
unit  of  force  acting  for  a  unit  of  time  on  a  unit  of 
mass  will  develop  a  unit  of  velocity,  and  the  unit  of  a 
mass,  multiplied  by  the  unit  of  velocity,  gives  a  unit 
of  momentum.  Then  introducing  the  element  of  mass 
into  the  formula,  v  =  ft,  we  have  mv  =  ft.  Multiplying 
both  sides  of  the  equation  by  n  units,  we  have  n  m  v  — 
n  f  t,  a  general  expression  for  the  generation  of  mo- 
mentum. (In  these  expressions,  t  signifies  one  unit  of 
time,  /  one  unit  of  force,  v  one  unit  of  velocity,  m  one 
unit  of  mass,  and  n  a  known  quantity.) " 

ACTION  AND  REACTION 

"According  to  a  well  established  principle  of  'ac- 
tion and  reaction,'  a  force  can  only  impart  motion  to 
a  mass  by  the  reaction  of  another  mass,  the  action  and 
reaction  being  equal  and  opposite.  As  a  positive  de- 
duction from  this  it  may  be  stated  that  if  we  find  a 
body  moving  in  a  given  direction  there  is  somewhere 
an  equal  and  opposite  motion.  The  first  and  most 


AEROPLANE  DETAILS  195 

elementary  way  of  expressing  this  motion  is  in  terms 
of  momentum;  and,  representing  the  opposite  direc- 
tions by  +  and  —  we  have  as  a  general  expression, 


Let  us  now  develop  this  formula  in  a 
special  line,  so  as  to  give  a  rational  explanation  to  what 
may  appear  as  an  absurdity  in  some  processes  which 
follow. 

"In  the  last  formula  let  v  =  v,,  +  vin  ;  then  substi- 
tuting  these   and    developing,   the   formula   becomes 

m^  Vi.   For  the  purpose  of  using  this 


m  Vu      m 

formula  to  illustrate  certain  points,  let  us  put  it  into 

figures. 

1  '  Let  m  =  1  ;  wt  =  2  ;  v±1  =  1  ;  Vm  =  i,  then,  from 
the  formula,  Vi  is  found  to  be  f.  We  now  place  these 
figures  in  order  and  leave  them  for  future  use. 


m  Vn  +  in  Via  ~       l  Vl 
1X1+1X4=2X1 


Momenta  = 


1  +  4 

IMPACT  OF  ELASTIC   BODIES 

"The  impact  of  elastic  bodies  presents  phenom^ 
ena  which  very  few  seem  to  have  studied,  still  fewer 
understand,  and  which  many  are  ready  to  deny  on 
general  principles.  And  because  of  certain  vague 
ideas  regarding  motion  and  the  exchange  of  momenta 
there  seems  to  be  an  inability  to  grasp  the  truths  de- 
rived from  some  of  the  mathematical  formulae,  or  to 
understand  the  phenomena  of  their  experimental  dem- 


196  VEHICLES  OF  THE  AIR 

onstrations.  To  have  a  proper  conception  of  these  one 
must  have  recourse  to  a  little  more  profound  study 
than  is  afforded  in  the  ordinary  text-books. 

'  l  In  the  present  discussion  all  that  I  hope  to  do  is  to 
give  a  demonstration  of  the  truth  of  some  of  the  prop- 
ositions, with  general  suggestions,  as  the  revolving  of 
the  subject  in  its  many  phases  would  be  too  lengthy. 

"In  presenting  the  formulae  of  the  impact  of  elastic 
bodies  I  shall  develop  a  special  case,  so  as  to  demon- 
strate that  what  appears  an  absurdity  is  a  rational 
conclusion  in  the  light  of  the  formula  of  action-and- 
reaction  just  developed.  These  are  general  formulae  for 
the  purpose  of  determining  the  velocities  of  two  elastic 
bodies  after  impact,  and  cover  all  possible  cases. 

"Let  A  and  B  represent  two  elastic  bodies,  having 
the  respective  velocities  F  and  U  ;  and  let  v  and  u  rep- 
resent their  velocities  after  impact. 

Then  (A  +  B)  v  =  2B  U  +  (A  —  B)  V 


"Substituting  these  values  in  the  formulae,  we  find, 
v  =  4  ;  u  =  $;  these  being  the  velocities  and  directions 
after  impact.  Multiplying  these  velocities  by  the  re- 
spective masses  gives  the  respective  momenta,  that  of 
A  being  4,  and  B,  1J.  This  latter,  to  many,  is  a  mani- 
fest absurdity  ;  for  as  the  original  momentum  of  A  is 
supposed  to  be  only  1,  how  can  it  give  14? 

"Let  us  analyze  the  problem,  and  assume  that  two 
equal  elastic  masses  m  =  1  and  mt  =  1,  are  acted  upon 
by  a  force  /,  which  imparts  a  velocity  1  to  each,  as  in 
Figure  64. 

"Let  Wi,  now  impinge  on  the  elastic  mass  M  =  2. 


AEROPLANE  DETAILS  197 

Then,  according  to  the  formulae  just  presented,  Wi  will 
rebound  from  M  with  a  velocity  v^  =  —  i.    If  this  be 


FIGURE  64 

so,  we  have,  on  one  side,  two  masses  having  a  velocity 
and  momentum  in  the  —  direction 

m  v  =  —  1,  Wi  Vn  =  —  i. 

"Eef erring  now  to  the  formula  of  action-and-reac- 
tion,  we  see  there  must  be  an  equal  and  opposite  mo- 
mentum in  the  +  direction  of  li,  and  this  we  find  in 
M  =  2,  with  V  =  l 

"Now  let  us  combine  these  ideas  with  those  pre- 
sented under  the  discussion  of  Figure  63,  and  we  have 
a  universal  expression  of  the  phenomena  of  action-and- 
reaction.  In  Figure  63  it  was  noted  that  with  a  given 
force  the  resulting  motion  of  momentum  was  de- 
pendent on  the  masses 
°WOM  IMWT  of  the  bodies  acted  upon. 
But,  it  is  apparent,  this  is 
not  final,  for  a  given 
force  /,  Figure  64,  acting 
on  m  and  ml9  generates 
FIGURE  GS  momenta  which  are  a 

proximate  result;  but  as 

Wt  impinges  on  another  mass  M  the  ultimate  result  of 
the  action  of  the  force  is  the  momentum  generated  in 
M.  In  this  case  mx  may  be  considered  a  force  acting 
on  M,  and  the  momentum  generated  is  measured  by 


198  VEHICLES  OF  THE  AIR 

the  intensity  multiplied  by  the  time,  and  the  time  is 
determined  by  the  inertia  of  the  masses. 

"An  inspection  of  the  system  presented  in  Figure 

64    shows    that    various 

\n)~- — *  <  ""  (m})$m  M3¥7  ideas  are  presented  ac- 
cording to  the  view 
taken.  One  is  that  the 
force  acting  on  mt  ulti- 
WTEKi  IWWT  mately  causes  it  to  move 
FIGUBK  ee  against ^  the  force,  an- 

other is  that  mi  im- 
presses upon  M  a  momentum  equal  to  its  impact  and 
reaction.  Further,  while  we  may  for  the  purpose  of 
drawing  special  deductions  fix  our  attention  on  the 
movement  of  one  or  another  of  the  masses,  we  must 
bear  in  mind  that  each  is  only  one  of  the  operating 
elements  in  a  system,  and  hence  must  not  be  consid- 
ered by  itself,  but  as  an  element  related  to  the  whole. 
Finally,  whatever  motion  any  of  the  elements  may 
have,  the  algebraic  sum  of  all  the  movements  in  the 
system  must  be  zero. 

"In  applying  the  formulae  of  the  impact  of  elastic 
bodies  to  the  case  of  two  equal  masses  m  and  mt1  Fig- 
ures 65  and  66,  if  m  be  moving  with  a  velocity  v  and 
nti  is  at  rest,  after  impact  Wi  moves  with  a  velocity  v, 
and  m  is  brought  to  rest.  But  if  the  masses  be  moving 
against  one  another,  with  the  respective  velocities  v 
and  Vi,  after  impact  mt  has  the  velocity  v,  while  m 
has  #1." 

IMPACT    OF   FLUIDS 

"The  elements  of  a  fluid,  being  elastic,  operate  in 
accordance  with  the  laws  just  stated,  but,  their  free 
movements  being  restrained  by  the  reactions  of  the 


'AEROPLANE  DETAILS  199 

surrounding  fluid,  their  impulses  are  propagated  as 
compression  waves,  which  in  their  movements  come 
under  the  same  laws,  as  the  well-known  experiments 

in  sound  prove.  But 
when  there  is  a  path  of 
least  resistance  the 
pressure  exerted  on  a 
fluid  gives  rise  to  a 
stream,  which  while 

not  being  elastic  as  a 

mass,  owing  to  its  fluid 

FIGURE  07  e 

nature,    produces    the 

same  set  of  actions  and  reactions  as  if  it  were.  For 
the  first  particles  which  reach  a  surface  impart  to  it 
the  momentum  of  their  impact,  and  then  are  forced 
away  by  the  compression  arising  from  those  following, 
and  hence  exert  another  element  of  pressure  by  their 
reaction." 

APPLICATION 

"Having  given  the  elementary  principles  involved, 
I  now  present  their  application  in  an  ideal  case,  in 
Figure  67,  in  which  a  and  ft,  in  the  views  to  the  right, 
are  two  equal  elastic  masses  moving  horizontally,  as 
indicated  at  h,  with  equal  velocities,  while  m  m  is  the 
elastic  surface  of  an  infinite  mass.  At  any  instant  let 
an  impulsive  force  /  act  on  a,  which  will  cause  it  to 
impinge  on  b,  the  two  masses  exchanging  their  mo- 
menta the  latter  will  take  the  path  b  c,  while  a  will 
continue  its  original  direction  towards  d.  But  b  will 
rebound  from  the  surface  m  my  and  take  the  direction 
c  d,  and,  coming  in  contact  with  a,  which  has  reached 
the  point  d,  will  impart  to  it  the  vertical  component  of 
its  motion,  causing  it  to  take  the  direction  a  e  while  b, 


200  VEHICLES  OF  THE  AIR 

having  lost  its  vertical  element  of  motion,  will  continue 
in  the  direction  d  g.  But  suppose  that  at  an  instant 
just  previous  to  this  impact,  another  impulse  /,  act 
upon  a,  then  the  two  masses  will  exchange  their  mo- 
menta, a  taking  the  direction  ae,  and  b  the  direc- 
tion b  m. 

"Examining  this  development,  we  find  that  the  first 
force  /  has  simply  set  up  a  series  of  actions  and  re- 
actions in  consequence  of  which  a  is  left  undisturbed 
while  b  impresses  on  m  m  the  force  of  its  action  and 
reaction,  these,  in  this  theoretical  case,  being  equal  to 
each  other  and  to  the  original  force  /.  After  the  second 
force  has  acted  on  a,  and  the  masses  have  exchanged 
their  momenta,  we  find  as  a  result  of  the  action  of  these 
two  forces  /  /,  and  the  reactions  of  a  and  b  and  m  m, 
that  there  are  two  elements  of  force  in  m  m,  and  one  in 
the  descending  mass  b,  while  a  has  an  ascending  veloc- 
ity theoretically  equal  to  the  downward  movement  im- 
parted by  the  first  impulse  /.  From  this  analysis  it 
appears  that  each  downward  impulse  imparted  to  a 
mass  may  be  transmitted  to  a  larger  mass,  which  while 
absorbing  all  the  original  impulse  gives  back  an  ele- 
ment of  reaction  which  in  turn  may  be  transmitted  to 
the  body  first  acted  upon,  giving  it  a  movement  op- 
posite to  that  given  by  the  first  force;  and  the  large 
mass  then  has  not  only  the  motion  due  to  the  action  of 
the  force,  but  also  that  due  to  the  reaction  of  the  mass 
moving  from  it. 

"In  these  demonstrations  we  have  one  element  of 
the  actions  and  reactions  taking  place  in  the  phenom- 
enon of  soaring — a  representing  the  bird,  b  the  air  im- 
mediately surrounding  it,  m  m  the  great  mass  of  sur- 
rounding air,  and  /  /,  the  impulses  of  gravity.  In  this 
demonstration  the  impulses  are  represented  as  distinct 
and  defined,  as  are  also  the  masses  a  b  and  m  m, 


AEROPLANE  DETAILS  201 

whereas  in  the  phenomenon  of  soaring,  the  action  of 
gravity  and  the  impacts  and  reactions  of  the  air  are 
continuous,  while  the  reflecting  mass  of  air  is  ever 
present  in  all  positions.  But  because  of  losses  due  to 
various  causes,  the  final  effect  is  far  below  the  ideal. 
The  formation,  adjustment,  and  forward  movement  of 
the  wing  surface,  are  only  the  means  by  which  the  air 
immediately  surrounding  is  thrown  into  the  movements 
by  which  these  elementary  processes  are  perpetuated. 

' i  To  have  a  complete  idea  of  the  process  of  soaring, 
suppose  that  an  appropriate  surface  be  held  in  the 
proper  position,  relative  to  the  horizontal,  as  shown  in 
Figure  59,  but  having  no  horizontal  motion.  Under 
the  influence  of  gravity  it  will  slowly  descend.  But  sup- 
pose it  receive  a  gradually-increasing  horizontal  veloc- 
ity, then  a  time  will  come  when  the  various  elements  of 
action  and  reaction  in  the  air  will  just  balance  the  im- 
pulses of  gravity,  and  the  surface  will  travel  in  a  hori- 
zontal direction;  then,  if  this  motion  be  further  in- 
creased, these  actions  and  reactions  over-balancing 
gravity  will  cause  it  to  rise,  the  rapidity  of  its  ascend- 
ing motion  depending  on  the  increase  in  velocity.  It 
must  be  noted,  that  these  various  changes  in  the  direc- 
tion of  movement,  are  due  to  a  variation  of  velocity 
alone,  for  the  surface  is  supposed  to  retain  the  position 
indicated  in  Figure  57,  and,  further,  owing  to  the  de- 
velopment indicated  in  Figure  62,  the  pressure  sup- 
porting it  tends  to  maintain  its  forward  movement,  or 
at  least  to  balance  the  retarding  resistances. 

"If  it  be  necessary  to  acquire  an  increase  of  veloc- 
ity, the  surface  may  be  slightly  inclined  and  a  new 
impetus  obtained,  whose  measure  is  not  the  distance  it 
descends  through  space,  but  that  through  the  rising 
current  of  air. 


202  VEHICLES  OF  THE  AIR 

"I  am  aware  various  objections  may  be  made,  based 
upon  the  common  principles  relative  to  bodies  descend- 
ing and  ascending  under  the  influence  of  gravity.  Be- 
garding  these  possible  objections,  I  shall  state,  that 
there  are  four  general  cases  involved  in  these  princi- 
ples— first  bodies  moving  in  free  space;  second,  an 
elastic  mass  let  fall ;  third,  the  movement  of  a  pendu- 
lum; fourth,  the  movement  of  a  ball  over  inclined 
planes. 

"  A  little  thought  will  reveal  the  fact  that  these  are 
only  special  expressions  of  the  great  fundamental  law 
of  action-and-reaction,  or  the  exchange  of  momenta, 
and  hence  are  not  to  be  used  as  a  standard  for  passing 
judgment  on  more  complicated  and  advanced  develop- 
ments of  the  same  basic  principles. 

"In  conclusion,  the  phenomenon  of  soaring  is  the 
practical  operation  of  a  principle  pointed  out  in  the  dis- 
cussion under  Figure  64 — that  a  force  may  act  on  a 
body  under  such  conditions  as  to  cause  the  body  to 
move  against  it.  One  important  and  practical  instance 
of  the  operation  of  this  principle  is  the  tacking  of  a 
ship  against  the  wind.  Of  course,  this  operation  has 
been  frequently  analyzed  and  explained,  but  underly- 
ing all  we  find  only  the  working  out  of  this  principle. 
So  it  is  with  the  analysis  relative  to  soaring,  with  this 
important  difference.  In  the  instance  of  the  tacking 
of  a  ship,  the  force  is  the  moving  air,  while  in  soaring 
it  is  the  pure  force  of  gravity.  In  the  first  instance, 
the  ship  tacks  against  the  wind,  but  as  an  essential  ele- 
ment in  the  process  must  move  through  a  more  or  less 
lateral  course,  while  in  the  second  the  bird  tacks 
against  gravity,  its  horizontal  motion  through  the  air 
being  only  an  element  in  the  process. 

"In  our  conception  of  these  operations,  we  should 


AEROPLANE  DETAILS  203 

not  fix  our  attention  too  closely  on  the  moving  objects, 
but  must  consider  them  as  only  one  of  the  elements  in  a 
system  of  moving  bodies. 

In  each  of  these  cases  we  have  four  factors^ 

First,  a  force,  the  wind,  acting  on,  second,  the  sails; 

Third,  the  hull,  acting  on,  fourth,  the  water. 

and 

First,  a  force,  gravity,  acting  on,  second,  the  mass; 

Third,  the  wings,  acting  on,  fourth,  the  air. 

"From  this  study  of  the  movements  of  fluids,  and 
the  special  laws  involved,  we  see  that  gliding,  or  soar- 
ing, flight  is  not  the  haphazard  dragging  of  an  inclined 
surface  through  the  air,  but  a  special  and  unique 
phenomenon  of  motion  and  energy,  and  holds  the  same 
relation  to  the  ordinary  phenomena  of  inclined  planes 
as  the  operation  of  the  gyroscope  does  to  the  simple 
rotation  on  a  fixed  axis.  And  in  the  process  of  soaring, 
there  are  not  only  the  form  and  adjustment  of  the  sur- 
face, but  also  the  proper  speed  and  manipulation  neces- 
sary to  produce  that  special  development  of  movements 
and  energy,  which  may  be  properly  termed  soaring. 

' l  In  other  words,  we  must  recognize  that  this  is  one 
of  the  operations  in  nature  based  upon  a  set  of  laws 
suited  to  itself;  and  we  must  realize  that  to  reach  the 
end  to  which  we  aspire  we  must  understand  what  these 
laws  are  and  follow  them  in  the  designing,  construc- 
tion, and  operation  of  our  devices." 


Flattened  Tips  to  wing  surfaces,  which  are  the 
rule  with  all  birds'  wings,  are  not  commonly  em- 
ployed in  modern  aeroplanes,  several  highly  suc- 
cessful machines  being  notable  offenders  in  this 


204  VEHICLES  OF  THE  AIR 

respect.  Fortunately  their  absence  does  not  ren- 
der a  construction  inoperative,  but  it  does  set  up 
wholly  unnecessary  forward  resistances,  which 
waste  power  and  impede  the  progress  of  the 
vehicle.* 

Angles  of  Chords  of  wing  sections  are  the 
" angle  of  incidence"  of  curved  surfaces.  For  the 
best  results  these  angles  should  be  very  flat  to  the 
path  of  movement — much  flatter  than  is  common 
practice,  in  which  the  use  of  inadequate  or  wrongly 
curved  surfaces  is  made  possible  to  considerable 
extents  by  the  employment  of  excessive  angles  of 
incidence.  A  method  of  determining  proper 
angles  of  incidence  is  explained  on  Page  186. 

WING  OUTLINES 

There  is  such  great  variety  in  the  wing  out- 
lines of  flying  animals  as  to  force  the  conclusion 
that  within  considerable  limits  the  wing  plan  does 
not  matter,  and  that  various  straight,  curved,  and 
irregular  front  and  rear  edges,  and  differences  in 
the  rounding  of  wing  tips,  may  be  determined  more 
by  structural  exigencies  than  by  laws  of  wing  ac- 
tion. 

Length  and  Breadth  do  vary  systematically, 
however,  the  one  rule  that  is  evident  in  the  bird 
mechanism  being  the  provision  of  long  and  narrow 
wrings  for  fast  soaring  flight  and  of  shorter  and 
broader  wings  for  slower  and  flapping  flight. 


*  The  points  involved  in  the  formation  of  the  ends  of  wing  surfaces 
are  referred  to  on  Page  189,  and  are  also  explained  in  the  closing  para- 
graphs of  the  Montgomery  patent  specification. 


AEROPLANE  DETAILS  205 

ARRANGEMENTS  OF  SUEFACES 

Besides  in  the  forms  and  outlines  of  the 
sustaining  surfaces  of  an  aeroplane  there  is  also 
possible  great  variety  in  their  number  and  arrange- 
ment. 

ADVANCING  AND  FOLLOWING  SUEFACES 

The  use  of  two  or  more  surfaces,  one  preceding 
another,  has  a  number  of  merits,  one  of  which  is 
the  compacting  of  the  supporting  areas  in  a  mini- 
mum space,  and  another  of  which  is  their  utiliza- 
tion to  afford  fore  and  aft  balance  (see  Page  221). 

SUPEEPOSED  SUEFACES 

The  use  of  pluralities  of  surfaces  in  vertical 
series  has  been  already  referred  to  in  the  discus- 
sion of  multiplanes  and  biplanes  commencing  on 
Page  168. 

STAGGEEED  SUEFACES 

Biplanes  with  the  upper  surface  set  ahead  of 
the  lower,  as  in  Figure  68,  have  been  built  to  secure 
the  supposed  advantage 
of  locating  the  two  sur- 
faces directly  above 
one  another,  not  in  ap- 
parent aspect,  but 
within  the  actual  flow  of  SI™* 

j-i  ,  ,   .    ,         right    angles. 

me  air  streams,  which 

approach  with  a  rising  trend  as  streams  indicated 

by  the  arrows.    A  recent  biplane  of  this  type, 


206  VEHICLES  OF  THE  AIR 

which  proved  only  indifferently  successful,  is  illus- 
trated in  Figure  69. 

LATEEAL  PLACINGS 

In  all  successful  aeroplanes  that  have  been  built 
the  sustaining  surfaces  extend  to  much  greater 
distances  laterally  than  they  do  in  any  other  direc- 
tion. This  limits  the  variety  of  practicable  com- 
binations. 

Separated  Wings,  with  either  an  open  interval, 
as  in  Figure  33,  or  the  body  of  the  machine  be- 
tween them,  are  the  commonest  construction  in 
monoplanes.  The  arrangement  closely  resembles 
that  of  the  animal  mechanism,  and,  similarly, 
is  probably  most  effective  when  the  body  has  a 
smooth  under  surface  and  sides  against  which  the 
wings  abut  closely  enough  to  prevent  any  flow  of 
air  through  the  juncture.  Several  such  construc- 
tions are  well  illustrated  in  Figures  171,  216,  222, 
247,  and  249. 

For  maintaining  lateral  balance,  widely  sepa- 
rated movable  wing  surfaces,  or  " ailerons",  are 
often  used,  but  these  are  not  main  sustaining  sur- 
faces (see  Page  217). 

Continuous  Wings  are  used  in  nearly  all  bi- 
planes, to  which  type  of  machine  they  are  pe- 
culiarly adapted.  In  such  vehicles  the  upper  sur- 
face usually  is  not  only  continuous  but  is  also  free 
of  attachments  and  obstructions,  while  the  lower 
surface  affords  at  its  center  mounting  for  the  en- 
gine, accommodation  for  the  operator,  etc.,  as  is 
shown  in  Figures  23, 172, 189, 190, 208, 224  and  248. 


AEROPLANE  DETAILS  207 

Lateral  Curvature  is  often  imparted  to  wing 
surfaces  for  one  reason  or  another — usually  in  not 
always  discriminating  though  often  effective  imi- 
tation of  the  similar  aspect  of  birds'  wings. 
Probably  the  best  form,  if  other  details  are  so  de- 
signed as  to  permit  it,  that  in  which  the  wing  ends 
droop  to  a  pronounced  extent,  as  in  the  machine 
illustrated  in  Figures  225, 226,  and  260,  which  from 
the  front  closely  resembles  the  soaring  attitude  of 
the  gull.  Another  instance  of  this  wing  form  was 
the  upper  surface  of  the  "June  Bug",  of  the 
Aerial  Experiment  Association.  In  this  biplane 
the  lower  surface  was  curved  up,  so  that  a  very 
favorable  form  for  structural  stiffness  was  realized 
in  addition  to  a  combination  of  the  merits  of  the 
drooped  wing  with  those  of  the  dihedral  form.  The 
Wright  machines,  which  appear  to  be  quite 
straight,  are  said  to  fly  best  when  so  trussed  that 
there  is  a  slight  droop  to  the  wing  ends. 

Dihedral  Angles  at  the  juncture  of  wing  pairs, 
as  in  the  Langley  model  illustrated  in  Figure  70, 
in  which  the  angle  was  135°,  have  the  merit  of  af- 
fording considerable  automatic  stability  in  calm 
air,  but  in  disturbed  air  have  just  the  opposite  ef- 
fect, the  low  position  of  the  maximum  weight  caus- 
ing the  invariable  trouble  that  results  from  thus 
placing  it — a  pendulum-like  oscillation  of  increas- 
ing amplitude  until  the  vehicle  overturns  (see  Page 
216).  Birds  often  soar  and  maneuver  with  their 
wings  in  the  dihedral  position,  but  their  ability  in- 
stantly to  adopt  other  positions  relieves  them  from 
the  risks  that  appear  when  the  angle  is  permanent. 


208  VEHICLES  OF  THE  AIR 


FIGURE  70. — Langley's  25-Pound  Double  Monoplane,  With  Wings  at  Dihedral 
Angle.  This  model  on  May  6,  1896,  flew  for  more  than  half  a  mile  over  the 
Potomac  River,  at  a  speed  of  about  20  miles  an  hour.  Subsequently,  on 
November  28,  1906,  with  a  similar  model  weighing  about  30  pounds,  a  three- 
quarter  mile  flight  at  about  30  miles  an  hour  was  achieved.  This  was  at  the 
end  of  a  three  years'  period  of  experimenting  that  had  for  its  object  the 
ultimate  production  of  a  man-carrying  machine.  The  size  of  the  heavier  model 
was  a  little  over  12  feet  from  tip  to  tip,  with  a  length  of  about  16  feet.  The 
whole  power  plant,  which  consisted  of  a  5-pound  boiler  and  a  26-ounce  non- 
condensing  steam  engine  that  developed  1%  horsepower,  weighed  about  7 
pounds.  Propulsion  was  by  bevel-gear  driven,  two-bladed  twin  screws,  rotating 
in  opposite  directions  behind  the  forward  surfaces  at  about  1,200  revolutions 
a  minute.  The  hull  was  metal  sheathed  to  protect  the  burner  from  the  wind, 
and  the  vessel  between  the  forward  surfaces  was  a  float  to  keep  the  machine 
up  when  it  alighted  upon  the  water.  In  conjunction  with  the  experiments 
with  a  man-carrying  machine,  which  terminated  with  the  unsuccessful  launch- 
ing on  December  8,  1903,  a  model  similar  to  the  above,  but  weighing  58 
pounds  and  having  66  square  feet  of  sustaining  surface — it  being  a  one- 
fourth  size  copy  of  the  large  machine — was  successfully  flown  with  its 
3-horsepower  motor. 

The  Bleriot,  Santos  Dumont,  and  Antoinette 
monoplanes  have  the  wing  surfaces  dihedrally 
placed,  as  is  evident  in  Figures  200,  215,  and  220, 
but  in  all  successful  models  of  these  aeroplanes  the 
angle  is  very  slight  and  its  merit  much  in  doubt. 
The  only  biplane  of  which  the  writer  knows  in 
which  dihedral  wings  were  used  was  the  not  very 
successful  machine  of  Ferber's,  illustrated  in  Fig- 
ure 224.  Nearly  all  modern  biplanes  are  built  with 
straight  or  almost  straight  wings. 

Many  soaring  birds  which  in  flight  set  their 
wings  at  a  drooped  or  flat  angle  are  observed  to 
hold  the  extreme  tips  of  their  wings  pronouncedly 
upturned — possibly  for  the  balancing  effect  of 


AEROPLANE  DETAILS  209 

the  dihedral  position,  though  this  is  by  no  means 
certain. 

VEETICAL  SUEFACES    . 

Surfaces  placed  vertically,  though  not  present 
in  any  flying  animal  except  the  varieties  of  flying 
fish,  are  found  quite  indispensable  in  man-made 
fliers,  in  which  they  are  made  to  serve  various  pur- 
poses, including  the  maintenance  of  lateral  bal- 
ance, and  the  effecting  of  lateral  steering  (see 
Pages  216  and  224).  Properly  placed,  they  also 
tend  to  keep  a  machine  to  a  desired  course  regard- 
less of  disturbing  influences,  or  headed  into  gusts 
of  wind  that  if  they  continued  to  come  from  one 
side  might  prove  very  dangerous.  To  meet  these 
latter  purposes  most  effectively,  the  vertical  sur- 
faces should  be  placed  to  the  rear,  as  in  the  ma- 
chine illustrated  in  Figures  225,  226,  227,  and  260, 
so  that  the  effect  of  side  gusts  always  must  be  to 
swing  the  machine  into  the  wind. 

The  use  of  large  vertical  surfaces  forward  is 
now  found  only  in  a  few  machines,  and  is  probably 
altogether  mistaken  design — a  conclusion  that  is 
especially  impressed  by  the  disuse  of  these  surfaces 
in  machines  of  the  Farman  and  Voisin  construc- 
tion, despite  the  fact  that  these  were  the  earliest 
and  most  consistent  adherents  of  this  design. 

Very  small  vertical  surfaces  in  the  forward 
elevator,  as  in  the  case  of  the  semicircular  surfaces 
jj,  Figure  185,  in  the  Wright  machines,  and  the  tri- 
angular surface  j,  Figure  229,  in  the  Curtiss  ma- 
chines, are  not  quite  so  uncommon  as  are  larger 


210  VEHICLES  OF  THE  AIR 

vertical  surfaces  in  front,  but  even  so  their  value  is 
decidedly  doubtful  unless  to  offset  some  other  de- 
fect in  design.  In  the  Wright  machines  these 
vertical  "half  moons"  are  not  rigidly  fixed  but  are 
allowed  a  few  inches  of  flapping  movement,  on 
their  diameters  as  the  axis,  under  the  influence  of 
side  gusts,  presumably  with  the  idea  that  they  thus 
tend  to  nose  the  front  of  the  machine  into  the  wind. 

SUSTENSION  OF  SURFACES 

The  sustaining  capacities  of  different  flat  and 
curved  aeroplane  surfaces  moved  through  the  air 
at  different  speeds  and  at  different  angles  of  in- 
cidence greatly  vary  with  every  new  combination 
of  the  innumerable  possible  factors.  Determina- 
tion of  the  most  suitable  surfaces  and  the  most  ad- 
vantageous conditions  therefore  has  long  been  one 
of  the  greatest  difficulties  in  the  way  of  aeronaut- 
ical progress. 

EFFECT  OF  SECTION 

As  has  been  previously  suggested  (see  Page 
171),  there  is  the  greatest  imaginable  difference  in 
the  sustaining  effect  of  different  wing  sections,  flat 
surfaces  being  quite  inferior  to  curved,  of  which 
the  best  are  more  or  less  exact  approximations  to 
parabolic  forms.  Moreover,  with  the  ideal  sur- 
faces there  are  very  curious  and  not  widely  under- 
stood relations  between  the  lift  and  drift — between 
the  amount  of  sustention  afforded  by  a  given  speed 
of  movement  and  the  resistance  (other  than  head 
resistances  and  skin  friction)  to  the  forward  move- 


AEROPLANE  DETAILS  211 

ment.  With  proper  design,  there  is  a  positive  for- 
ward inclination  to  the  sustaining  force,  or  lift, 
which,  instead  of  being  normal  to  the  chord  of  the 
surface  or  to  its  direction  of  movement,  is  inclined 
forward  to  an  extent  sufficient,  with  certain  angles 
and  certain  curves,  wholly  to  overcome  the  drift 
(see  Page  190),  which,  therefore,  becomes  a  phe- 
nomenon pertaining  only  to  incorrect  surfaces. 

EFFECT  OF  ANGLE 

Measured  as  a  proportion  of  the  unit  resistance 
met,  when  a  given  surface  is  opposed  flatwise  or 
with  its  chord  at  right  angles  to  the  air,  the  values 
of  lift  and  drift  with  different  surfaces  can  be 
tabulated  in  percentages  of  this  "normal"  at  dif- 
ferent speeds  and  different  angles.  Many  such 
tables  have  been  prepared — most  successfully  by 
empirical  investigations — and  from  these  tables  it 
has  been  attempted  to  deduce  working  formulas  by 
which  to  solve  the  variety  of  practical  problems 
that  can  arise  in  given  cases.  Unfortunately  these 
formulas  have  been  found  not  to  work  out  cor- 
rectly in  practice  to  any  considerable  extent,  and 
many  inaccuracies  are  now  known  to  exist  in  the 
most  highly  regarded  tables,  such  as  those  of 
Smeaton  and  of  Lilienthal,  the  latter  of  wrhich 
are  widely  considered  fairly  correct — though 
slightly  too  high  at  very  small  angles. 

EFFECT  OF  SPEED 

The  many  formulas  that  are  more  or  less  widely 
used  in  calculating  the  effect  of  speed  upon  the 
sustention  of  different  surfaces  cannot,  in  the  light 


212  VEHICLES  OF  THE  AIR 

of  recent  developments  in  the  science  and  practice 
of  aeronautics,  be  accepted  as  correct  except  within 
very  narrow  limits  or  in  a  very  general  way.  It  can 
be  safely  asserted  only  that  the  sustention  in- 
creases much  faster  than  the  speed — possibly  with 
its  square. 

Particularly  interesting  in  this  connection, 
rather  than  especially  exact,  is  the  glimmer  of  truth 
in  "Langley's  law" — according  to  which  the 
power  required  for  propelling  an  aeroplane  sur- 
face through  the  air  indefinitely  diminishes  as  the 
speed  increases. 

EFFECT  OF  OUTLINE 

With  all  other  conditions  equal  the  sustention 
of  a  surface  is  subject  to  variation  with  change  of 
outline — particularly  with  difference  in  width  (see 
Page  184) .  No  adequate  explanation  of  this  phe- 
nomenon is  known  other  than  that  contained  in  the 
reference  cited. 

EFFECT  OF  ADJACENT  SURFACES 

A  given  surface  moved  through  the  air  under 
given  conditions  will  invariably  afford  greater  sup- 
port when  alone  than  when  adjacent  to  other  sur- 
faces. In  a  biplane  the  sustention  of  the  upper  sur- 
face is  always  materially  lower  than  that  of  the 
lower  surface,  especially  if  the  separation  of  the 
surfaces  is  insufficient  or  the  forward  speed  very 
low.  In  the  case  of  following  surfaces,  as  in  Figures 
97  and  225,  at  least  partial  correction  for  the  ad- 
jacent disturbance  of  the  air  can  be  had  by  making 


AEROPLANE  DETAILS  213 

the  two  surfaces  of  different  form  and  inclination 
(see  Page  248). 

CENTER  OF  PEESSURE 

The  center  of  pressure  of  a  sustaining  surface 
is  the  lateral  axis  on  which  the  load  is  balanced 
(see  Page  181  and  Figure  62).  With  wrong  sur- 
faces at  wrong  angles  the  center  of  pressure  is  a 
most  elusive  and  variable  factor,  tending  always 
to  uncertain  and  precarious  equilibrium,  but  with 
correct  surfaces  it  can  be  very  definitely  located 
and  equilibrium  maintained  by  keeping  the  center 
of  gravity  beneath  it. 

HEAD  RESISTANCES 

Contrary  to  the  popular  notion,  the  forward  re- 
sistances encountered  in  moving  any  object 
through  the  air,  no  matter  what  its  form,  are 
closely  related  to  the  " projected  area",  being  little 
influenced  by  " wind-cutting"  shapes,  thin  edges, 
and  other  misguided  expedients  to  reduce  this  re- 
sistance. This  is  experimentally  proved  in  the 
use  of  racing  automobiles,  which  at  speeds  in  ex- 
cess of  100  miles  an  hour  do  not  measurably  differ 
in  their  head  resistances  whether  they  have  flat 
or  elaborately  pointed  fronts.  Projectiles,  even,  of 
the  common  pointed  ogival  forms  do  not  travel  at 
velocities  perceptibly  greater  than  can  be  obtained 
under  otherwise  similar  conditions  with  flat- 
fronted  projectiles.  The  reason  for  this  seemingly 
anomalous  effect  appears  to  be  that  in  case  of  a 
flat  or  blunt  surface  there  is  carried  on  the  front 


214  VEHICLES  OF  THE  AIR 

of  the  visible  structure  an  invisible  cushion  of  com- 
pressed air — varying  in  its  length  and  form  in  ac- 
cordance with  the  speed,  but  always  automatically 
created  to  the  exact  shapes  best  calculated  to  pene- 
trate and  part  the  main  body  of  the  atmosphere 
in  most  effective  manner. 

Against  flat  surfaces  moved  through  the  air,  the 
pressure  is  usually  stated  to  vary  with  the  square 
of  the  velocity,  a  surface  one  foot  square  placed  at 
90°,  as  in  Figure  42,  receiving  pressures  as  follows, 
according  to  one  authority  :* 

Speed  of  movement  In  miles  per  hour        7        14        21       41       61        82        92 
Pressure  in  pounds  per  square  foot.     .2         .9       1.9       7.5     16.7     30.7     37.9 

At  twenty-five  miles  an  hour  the  surface  re- 
ceives a  pressure  of  3.24  pounds,  while  when  it  is 
inclined  to  15°  from  the  direction  of  the  current 
this  pressure,  or  drift,  is  reduced  to  .33  pounds, 
with  a  lift  of  1.5  pounds,  as  is  made  clear  in  Figure 
42.  The  ratio  of  lift  to  thrust  greatly  increases  as 
the  inclination  decreases. 


*  According  to  a  table  compiled  for  the  ' '  Mechanical  Engineer 's 
Pocket  Boole,"  the  pressures  on  a  square  foot  of  flat  surface  in  dif- 
ferent winds  are  as  follows: 

MILKS  PER  HOUR  CLASSIFICATION  or  WIND        PRESSURE  ON  SQUARE  FOOT 

1 Hardly  perceptible  .005  Pounds 

2 Just  perceptible  .02 

3 Just  perceptible  .044 

4 Gentle  breeze  .079 

5 Gentle  breeze  .123 

10 Pleasant  breeze  .492 

15..            Pleasant  breeze  1-107 

20 Brisk  gale  1.968 

25 Brisk  gale  3.075 

30 High  wind  4.428 

35   .                   High  wind  6.027 

40..                  ...  .Very  high  wind  7.872 

45 Very  high  wind  9-963 

50 Storm  12.300 

60 Great  storm  il'Ina 

70 Great  storm  24.108 

80 Hurricane  3i '« 

100 Hurricane  49.2 


'AEROPLANE  DETAILS  215 

Though  not  especially  affected  by  the  form  of  a 
surface,  head  resistance  is  affected  by  the  extent 
of  surface,  being  lower  per  unit  of  area  on  small 
areas  than  it  is  on  large.  This  is  because  the  air 
centrally  in  front  of  a  large  surface  must  be  dis- 
placed to  a  greater  extent  laterally  to  pass  the  sur- 
face than  is  necessary  with  a  small  surface.  Also, 
the  rear  form  of  an  object  is  of  importance,  a  blunt 
front  and  finely  tapered  rear  outline  being  that 
calculated  to  displace  and  reform  the  air  streams 
with  the  expenditure  of  the  least  energy. 

BALANCING 

An  aeroplane  can  only  tip  over  sideways  or  end- 
ways, consequently  to  maintain  it  right-side  up  can 
require  provision  only  for  maintaining  lateral  and 
longitudinal  equilibrium. 

LATEBAL  BALANCE      ' 

It  is  now  well  established  both  from  observa- 
tion of  flying  animals  and  in  the  construction  of 
flying  machines  that  there  is  a  considerable  number 
of  ways,  all  more  or  less  effective,  of  maintaining 
the  lateral  balance  of  an  aeroplane.  These  methods 
are,  moreover,  capable  of  use  both  independently 
and  in  various  combinations.*  Furthermore,  some 
of  them  are  of  a  nature  to  operate  automatically 
against  disturbing  forces,  whereas  others  require 
actuation  by  controlling  means. 

*  Many  birds  obviously  employ  wing  warping,  tilting  and  swinging 
of  wing  tips,  variation  of  wing  areas  and  angles,  and  shifting  of  the 
weight,  in  a  great  variety  of  combinations. 


216  VEHICLES  OF  THE  AIR 

Vertical  Surfaces  for  maintaining  balance  are 
analogous  to  the  similar  use  of  such  surfaces  in  box 
kites,  and  act  in  a  most  effective  and  wholly  auto- 
matic manner — any  tilting  bringing  the  side  of  the 
vertical  surface  that  is  towards  the  inclination  into 
play  as  a  more  or  less  effective  lifting  surface  (ac- 
cording to  the  extent  of  the  tilting) ,  with  the  result 
that  the  air  pressures  promptly  force  it  back  to  its 
normal  position.  As  has  been  previously  explained 
(see  Page  209),  it  seems  for  a  number  of  excellent 
reasons  inadvisable  to  place  vertical  surfaces  any- 
where but  at  the  rear  of  a  machine. 

Dihedral  Angles  of  wings  operate  similarly  to 
vertical  surfaces  in  maintaining  balance,  being  in 
their  normal  position  at  angles  of  less  than  their 
maximum  effectiveness,  so  that  tilting  of  the 
vehicle  renders  the  lowered  wing  more  effective 
and  thus  automatically  corrects  itself.  The  objec- 
tions to  dihedral  wings  are  explained  on  Page  207. 

Wing  Warping  as  a  means  of  steering  or  bal- 
ancing, for  which  it  is  used  in  the  modern  Wright, 
Bleriot,  Montgomery,  and  other  machines,  consists 
of  a  simple,  unsymmetrical  twisting  of  the  wing 
ends  by  any  suitable  means  so  as  to  transfer  the 
maximum  lift  from  one  side  of  the  machine  to  the 
other  by  varying  the  angles  of  wing-tip  inclination 
to  the  line  of  travel.  This  method  of  balancing, 
which  is  perhaps  the  most  effective  known,  was 
patented  in  Prance  by  D'Esterno,  was  used  by  Le 
Bris,  and  was  first  patented  in  the  United  States 
by  Mouillard  (see  Figure  262).  Another  early 


AEROPLANE  DETAILS  217 

recognition  of  its  merits  appears  in  the  Scientific 
American  Supplement  of  June  4, 1881,  in  which,  in 
an  article  on  aeronautics  by  Tim  Choinski,  it  is  re- 
marked that  "  When  a  flying  bird  wants  to  go  side- 
wise  or  turn,  it  slopes  backward  to  an  inclined 
plane  but  one  wing  of  that  side  where  it  wants  to 
go."  Despite  the  numerous  early  recognitions  of 
the  value  of  wing  warping  it  did  not  appear  in 
combination  with  otherwise  successfully  operative 
mechanisms  until  within  comparatively  recent 
years.  Its  application  to  the  Wright,  Bleriot,  and' 
Montgomery  machines  is  shown  in  Figures  185, 
197,  and  225.  An  objection  to  wing  warping  as  it 
has  been  commonly  applied  is  that  the  abrupter  in- 
clination of  that  end  of  the  wing  may  cause  a 
greater  resistance  to  and  consequent  slowing  of 
the  side  of  the  vehicle  which  should  go  the  fastest 
in  executing  a  turn — it  being  necessary  in  some 
aeroplanes  to  resist  this  tendency  by  the  simulta- 
neous manipulation  of  rudder-like  vertical  sur- 
faces. 

Tilting  Wing  Tips,  capable  of  being  thrown  up 
or  down  into  positions  less  effective  than  the  nor- 
mal, constitute  a  means  of  balancing  that  was 
tried  by  Maxim,  and  which  would  seem  at  least 
to  present  the  advantage  of  avoiding  the  variation 
in  forward  resistances  referred  to  in  the  preceding 
paragraph. 

Hinged  Wing  Tips,  or  " ailerons",  adjacent  to 
the  end  or  the  rear  edges  of  the  wing  tips  proper, 
or  wholly  separated  from  these  in  the  case  of 
several  biplanes,  are  a  common  and  successful 


218  VEHICLES  OF  THE  AIR 

means  of  maintaining  lateral  balance  without  re- 
course to  wing  warping.  Typical  aileron  arrange- 
ments are  clearly  shown  at  a  a  a  a  in  Figures  76,  77, 
78,  79,  80,  and  81. 

Variable  Wing  Areas,  while  a  common  maneu- 
ver with  many  birds,  have  not  yet  been  provided 
for  in  any  successful  flying  machine.  A  suggested 


FIGURE  82. — Sliding  Wing  Ends. 

method  of  varying  wing  areas  is  illustrated  in 
Figure  82.  It  is  evidently  analogous  to  shifting  the 
weight,  securing  practically  the  same  result. 

Shifting  Weight  as  a  means  of  controlling 
lateral  balance  was  first  practically  employed  by 
Lilienthal,  and  subsequently  by  Pilcher,  Chanute, 
and  others.  In  some  of  their  early  experiments 
the  Wrights  controlled  the  wing  warping  by  a 
movement  of  the  operator's  body  side  wise  in  a 
cradle-like  control  frame,  thus  securing  a  combina- 
tion of  warping  with  weight  shifting  (see  Page 
229).  One  very  serious  objection  to  shifting 
weight  is  that  it  requires  extraordinary  acrobatic 
skill  to  apply  this  method  successfully. 

Rocking  Wings,  pivoted  at  their  point  of  attach- 
ment to  the  body  of  the  machine,  are  a  very  old 
idea.  A  notable  application  of  this  principle  in  a 
successful  modern  monoplane  is  found  in  some 
recent  Antoinette  machines,  in  which  the  lateral 
balancing  is  effected  solely  by  dissimilar  rocking 


AEROPLANE  DETAILS 


219 


of  the  entire  wings.  One  of  these  machines  is 
illustrated  in  Figures  215  and  216.  A  most  unusual 
application  of  rocking  wings  is  that  in  the  Cody 
biplane  (see  Figure  202),  in  which  they  appear  in 
the  forward  elevator  and  serve  to  control  either 
lateral  or  longitudinal  balance,  according  to 
whether  they  are  rocked  oppositely  or  together. 

Swinging  Wing  Tips  are  another  feature  of  bird 
mechanism  that  offers  interesting  possibilities  of 
application  to  aeroplanes.  This  idea  was  probably 
first  used  by  Chanute  in  his  patented  construction 
described  on  Page  462,  and  illustrated  in  the  form 
preferred  by  him  as  a  result  of  his  experiments,  in 
Figure  261,  in  which  the  movement  of  the  wing  tips 


FIGUBK  83. — Swinging  Wing  Ends. 

was  effected  solely  by  variations  in  wind  pressure. 
A  control-manipulated  system  of  swinging  wing 
tips  is  suggested  in  Figure  83,  It  is  an  idea  of  the 
writer's  that  if  in  this  the  wing  tips  a  a  a  a  be  given 
a  down  curve  at  their  ends,  thus  approximating  a 
correct  wing  section  in  two  directions,  the  result  of 
swinging  them  to  the  rear  will  be  to  increase  the 
sustention  and  the  tangential  component  forward 
while  at  the  same  time  reducing  head  resistance. 
This  would  afford  an  ideal  method  of  steering  and 
close  observation  is  convincing  to  the  effect  that 
it  is  a  method  used  by  many  birds. 


220  VEHICLES  OF  THE  AIR 

Plural  Wing  Tips  are  plainly  existent  in  the 
finger-like  separated  tip  feathers  of  the  wings  of 
many  soaring  birds.  The  exact  utility  and  manipu- 
lation of  this  type  of  wing  is  a  mystery  still  await- 
ing satisfactory  explanation,  and  perhaps  contain- 
ing the  secret  of  some  most  advantageous  construc- 
tion. 

LONGITUDINAL  BALANCE 

Longitudinal  balancing  means  are  necessary  for 
two  purposes — primarily  to  prevent  forward  or 
backward  upsetting  of  the  vehicle  and  secondarily 
to  provide  means  of  steering  on  up  or  down  slants 
of  air.  As  in  the  case  of  lateral  balance,  the  prob- 
lem of  longitudinal  balance  is  one  that  admits  of  a 
variety  of  solutions. 

By  Front  Rudders,  or  " elevators",  the  hori- 
zontal course  of  an  aeroplane  can  be  effectively 
kept  under  control,  as  is  well  proved  in  the  case 
of  many  modern  aeroplanes  (see  Figures  80,  172, 
187, 196,  207,  208,  209,  211,  and  229).  This  elevator 
placing  is  more  common  to  biplanes  than  to  mono- 
planes. 

By  Rear  Rudders  practically  the  same  effects 
can  be  had  as  with  front  rudders,  the  placing  being 
therefore  a  matter  of  choice  or  of  minor  considera- 
tion. Typical  rear-rudder  arrangements  for  con- 
trolling fore-and-aft  balance  are  shown  at  h  h  in 
Figures  85,  216,  217,  222,  and  229,  in  the  latter  of 
which  it  will  be  noted  that  both  front  and  rear 
elevating  surfaces  are  provided. 

Box  Tails  as  longitudinally  stabilizing  elements 


AEROPLANE  DETAILS  221 

are  found  highly  effective  and  almost  automatic. 
The  most  important  present  examples  of  this  con- 
struction are  the  Farman  and  Voisin  machines 
(see  Figures  81,  207,  and  211). 

Shifting  Weights  for  maintaining  longitudinal 
balance  are  even  less  suitable  than  for  lateral  bal- 
ancing (see  Page  218).  In  the  Weiss  monoplane 
an  unsuccessful  attempt  was  recently  made  to  ap- 
ply this  principle,  the  weight  sliding  on  wires  and 
being  actuated  by  a  lazy-tongs  device. 

Plural  Carrying  Surfaces  are  commonly  pro- 
vided as  important  features  in  the  design  of  many 
modern  aeroplanes.  And,  indeed,  unless  definitely 
made  to  operate  against  the  air  above  them  as  well 
as  that  below  them,  as  in  the  case  of  the  Wright 
flexible  elevator  (see  Figure  84),  it  is  necessary 
that  elevator  surfaces  carry  some  weight  if  their 
action  is  to  be  effective.  This  being  the  case,  the 
proportion  of  the  weight  carried  on  the  elevator 
will  be  in  proportion  to  the  relation  of  its  area  to 
that  of  its  main  surfaces.  An  extreme  example 
of  the  possibilities  in  this  direction  appears  in  the 
Montgomery  double  monoplane  (see  Figure  225), 
in  which  the  two  main  sustaining  surfaces,  though 
equal  in  area,  can  be  variably  inclined  to  each  other 
for  the  purpose  of  controlling  longitudinal  equi- 
librium (see  Page  220). 

AUTOMATIC   EQUILIBRIUM 

In  its  common  significance  this  term  has  come  to 
be  descriptive  of  means  or  devices  for  correcting 
an  aeroplane's  deviations  from  its  normal  level 


222  VEHICLES  OF  THE  AIR 

automatically,  independent  of  the  attention  of  the 
operator.  In  the  majority  of  projects  for  its  appli- 
cation it  is  designed  to  effect  only  the  lateral  con- 
trol— the  fore-and-aft  control  remaining  in  the 
hands  of  the  operator  as  a  necessary  means  of  gov- 
erning descent  and  ascent. 

Arrangement  of  Surfaces  is  probably  the 
simplest  as  well  as  the  most  effective  means  of 
maintaining  lateral  balance  automatically,  as  is  ex- 
plained on  Page  216,  where  the  effect  of  vertical 
surfaces  is  set  forth  in  detail. 

Electrical  Devices  for  securing  equilibrium  are 
of  a  class  that  automatically  correct  rather  than 
maintain  balance  of  a  machine,  and  even  in  their 
simplest  forms  are  of  a  complication  requiring  that 
hand  control  be  always  ready  to  supplement  their 
action  if  disaster  is  not  to  be  deliberately  courted. 
One  proposal  for  an  electrical  balancing  device 
involves  primarily  a  bent  glass  tube  in  which  a 
small  quantity  of  mercury  makes  and  breaks  differ- 
ent contacts  as  the  vehicle  tilts  in  different  direc- 
tions. Through  these  contacts  power  is  applied  to 
the  devices  that  must  be  manipulated  to  rectify 
the  equilibrium. 

The  Gyroscope,  because  of  its  peculiar  property 
of  resisting  forces  that  tend  to  shift  its  plane  of 
rotation,  can  be  so  mounted  as  to  remain  in  a  given 
position  irrespective  of  the  movements  of  its  sur- 
roundings. In  this  way  a  secondary  control  can 
be  maintained  over  stabilizing  surfaces  by  the  auto- 
matic distribution  of  power  for  their  manipulation. 
Another  way  of  utilizing  the  gyroscope  is  by 


AEROPLANE  DETAILS  223 

making  it  comparatively  heavy  and  mounting  it 
solidly  on  a  vertical  axis.  The  most  impractical 
feature  of  this  plan — the  weight  involved — it  is 
proposed  to  escape  by  utilizing  as  gyroscopes  parts 
of  the  machine  that  are  required  in  some  form  in 
any  case,  as  the  flywheels  of  engines,  etc. 

Compressed  Air,  or  " fluid  pressure",  has  been 
planned  for  as  a  means  of  transmitting  balancing 
manipulations  to  aileron  and  elevator  surfaces  in  a 
patent  issued  to  the  Wright  brothers  in  England. 
In  this  system,  the  initial  control  is  effected  by  the 
variation  of  the  air  pressures  on  specially  provided 
vanes,  or  by  the  swinging  of  a  pendulum. 

The  Pendulum,  preferably  swung  in  a  reservoir 
of  oil  or  other  liquid  to  suppress  violent  oscilla- 
tioss,  has  been  often  suggested  as  a  possible  means 
to  automatic  stability,  but  attempted  applications 
have  met  with  no  more  success  than  has  attended 
efforts  to  make  practical  use  of  other  systems  of 
automatic  balancing. 

STEEEING 

The  steering  of  modern  aeroplanes  is  a  problem 
that  presents  so  few  difficulties  that  it  has  been 
more  or  less  successfully  solved  in  a  considerable 
variety  of  constructions,  all  of  which,  however,  are 
subject  to  certain  effects  and  conditions  that  must 
be  reckoned  with  by  the  experimenter. 

EFFECTS  OF  BALANCING 

In  balancing  an  aeroplane  laterally  by  the 
means  at  the  present  time  most  preferred,  there  is 


224  VEHICLES  OF  TEE  AIR 

in  most  constructions  a  pronounced  steering  as  well 
as  the  balancing  effect.  Thus  in  wing  warping 
systems  the  manipulation  of  the  wing  ends  is  a 
most  effective  means  of  steering  and  in  several 
machines  is  definitely  so  used.  In  such  steering, 
however,  it  may  be  necessary  to  counteract  the  lag 
of  the  most  inclined  tip  (see  Page  217)  either  by 
the  side  resistance  of  a  large  fin  or  by  the  manipu- 
lation of  a  smaller  rudder. 

VERTICAL  RUDDERS 

Vertical  rudders,  in  the  proper  significance  of 
the  term,  are  rudders  used  for  lateral,  or  hori- 
zontal, steering,  wherefore  they  must  be  placed  ver- 
tically. This  fact,  and  a  considerable  inconsistency 
in  different  writers'  use  of  the  term,  has  given  rise 
to  no  small  amount  of  confusion,  which  can  be  dis- 
pelled only  by  more  general  agreement  as  to  what 
terms  are  to  mean.  Perhaps  the  easiest  escape 
from  the  difficulty  is  to  be  found  in  the  English 
substitution  of  " elevator"  for  horizontal  rudder, 
leaving  the  " vertical  rudder",  placed  vertically  for 
steering  on  a  horizontal  plane,  to  be  known  simply 
as  the  rudder. 

Pivoted  Eudders,  as  shown  at  i,  Figures  85, 
198,  209,  216,  224,  and  229,  and  in  Figure  195,  are 
the  common  form,  though  perhaps  not  the  most 
meritorious. 

Flexible  Rudders,  of  the  type  illustrated  in 
Figure  84,  which  is  taken  from  the  drawings  of  a 
patent  issued  to  the  Wright  brothers,  have  the 
merit  that  they  always  present  curved,  instead  of 


FIGURE  85. — Rear  Controls  of  Antoinette  Monoplane.  In  this  hh  are  horizontally-pivoted 
surfaces  for  steering  up  or  down  ;  I  is  a  vertically  pivoted  surface  for  steering  sidewise ;  and 
;  is  a  vertical  fin  used  for  its  stabilizing  effect. 


FIGURE  86. — Double  Control  from  Single  Wheel.  As  is  very  apparent  from  the  system 
shown  in  this  illustration,  two  distinct  movements  can  be  readily  produced  by  manipulation 
of  a  single  wheel.  For  example,  the  cords  passing  around  the  pulley  at  a  can  be  extended 
to  operate  wing  tips,  instead  of  the  vane  6,  when  the  wheel  is  revolved,  while  the  link  c  can 
as  well  be  connected  to  a  vertical  rudder  as  to  the  arrow  d. 


' 
i  .    -'<^; 


AEROPLANE  DETAILS 


225 


the  less  effective  flat  surfaces,  to  the  air  they  work 
against.     Obviously  this   principle   of  construe- 


"•"-•.-.. 

.^^ 

f 

*?-T 

i 

00 

2 

1^3^ 

§<.;  ; 

.'->''''''"   J 

FIGURE  84. — Wright  Flexible  Elevator  or  Rudder.  When  the  hand  lever  is 
moved  into  either  of  the  positions  shown  by  the  dotted  lines  the  steering  sur- 
faces are  correspondingly  sprung  into  curved  form,  presenting  approximately 
correct  surfaces  to  the  air  above  or  below  them,  as  the  case  may  be.  This 
springing  is  due  to  the  pivotal  points  of  the  surfaces  being  not  in  line  with  the 
pivot  of  the  actuating  bar  between  them. 

tion  is  applicable  to  either  vertical  or  horizontal 
rudders. 

HOKIZONTAL  RUDDERS 

Horizontal  rudders,  or  elevators,  usually  con- 
trol not  only  the  vertical  steering  but  also  serve  to 
maintain  the  longitudinal  equilibrium.  Conse- 
quently they  serve  a  secondary  function  as  sustain- 
ing surfaces,  for  which  reason  it  has  been  already 
necessary  to  accord  them  fairly  exhaustive  con- 
sideration (see  Page  220). 

TWISTING  RUDDERS 

Eudders  of  the  type  illustrated  at  h  in  Figure 
222  are  in  a  class  by  themselves.  It  has  been  ex- 
plained (see  Page  161)  that  flying  fish  are  the  only 
ones  of  nature's  flyers  normally  provided  with  ver- 
tical surfaces,  but  this  statement  perhaps  disre- 
gards the  fact  that  most  birds,  by  twisting  move- 
ments of  their  tails,  are  able  to  use  these  as  vertical 


226  VEHICLES  OF  THE  AIR 

rudders.  In  the  R.  E.  P.  rudder  just  referred  to 
it  is  sought  to  imitate  this  action  by  providing  a 
rudder  with  a  revolving  as  well  as  flexing  move- 
ment so  that  it  can  be  opposed  to  the  air  in  any 
possible  direction.  There  is  no  question  of  the 
effectiveness  of  such  an  action,  but  the  problem  of 
a  suitable  controlling  mechanism  for  it  is  another 
and  more  difficult  matter. 

CONTROLLING  MEANS 

The  number  and  complexity  of  controlling 
movements  involved  in  the  operation  and  piloting 
of  an  aeroplane  have  long  constituted  one  of  the 
greatest  bars  to  progress  in  this  field  of  engineer- 
ing, and  still  present  some  of  the  most  difficult  of 
its  unsolved  problems. 

Man  being  a  creature  possessed  of  only  two  feet 
and  two  hands,  and  flight  ordinarily  requiring — as 
displayed  by  the  birds — a  variety  of  manipulations 
delicate  and  vigorous,  quick  and  slow,  simple  and 
complicated,  which  man  can  scarcely  hope  to  imi- 
tate, the  difficulty  of  producing  them  in  unfailingly 
effective  coordination  must  be  apparent. 

For  there  are  lateral  and  longitudinal  balance 
to  be  maintained,  vertical  and  horizontal  steering 
to  be  effected,  a  motor  to  regulate  and  adjust,  in- 
struments and  devices  to  be  watched,  and  the  spe- 
cial conditions  of  starting  and  landing  to  be  en- 
countered— f  rom  all  of  which  it  might  appear  that 
the  average  aviator  must  at  least  find  sufficient  to 
occupy  his  attention  if  none  of  these  functions  are 
performed  automatically. 


control™  f '~ Shouflder-Fork  ControL  This  is  a  characteristic  example  of  the  means  of 
engages  the  .h^  "of  the^t^JTi  ^.^^  ^^^^ 
the  balancmg  mechanisms  of  the  biplane-by  the  natural  swing  of  the  operator's  body. 


AEROPLANE  DETAILS  227 

But  problems  do  not  exist  without  roads  to 
their  solution,  and  already  in  man's  advancing 
mastery  of  the  air  much  progress  has  been  made 
in  the  devising  of  simple  and  effective  controlling 
systems,  while  more  simple  and  more  effective  sys- 
tems are  quite  in  prospect. 

COMPOUND  MOVEMENTS 

One  of  the  most  effective  methods  of  control  is 
the  combination  of  two  or  more  movements  in  a 
device  manipulated  by  a  single  hand.  A  charac- 
teristic example  is  given  in  Figure  86,  which  is 
substantially  that  employed  in  the  Voisin  and  Cur- 
tiss  machines  (see  Figures  202  and  228).  Another 
example  is  the  lever  that  controls  the  wing  warp- 
ing and  the  vertical  rudder  in  the  Wright  machines 
(see  Figures  185  and  190). 

PLURAL  OPERATORS 

A  plurality  of  operators  in  steam  and  sailing 
vessel  navigation  is  the  rule  in  all  but  the  smallest 
craft,  larger  ships  being  not  capable  of  manage- 
ment by  a  single  individual.  In  the  largest  steam- 
ships the  pilot,  upon  whom  devolves  the  steering 
and  the  general  control  of  the  vessel,  has  no  direct 
means  of  causing  it  to  change  its  speed,  stop,  or 
go  astern — these  maneuvers  being  solely  in  the 
hands  of  the  engineer,  with  whom  the  pilot  is  in 
communication  by  signals.  Similarly,  in  locomo- 
tive operation,  control  of  the  steam  pressure  and 
fire  falls  to  the  fireman  or  stoker,  while  the  throttle, 
brake  handles,  etc.,  are  left  to  the  engineer  or 
driver. 


228  VEHICLES  OF  THE  AIR 

In  flying  machines,  except  in  the  case  of  diri- 
gible balloons,  the  only  use  of  two  operators  of 
which  the  writer  knows  is  ascribed  to  the  Wrights, 
who  are  said  to  have  operated  their  early  three- 
lever  machine  together. 

In  further  development  of  flying  machines  the 
chief  need  for  two  operators  would  appear  to  be 
most  required  as  a  means  of  maintaining  the  motor 
and  the  machine  generally  in  continuously  and 
safely  operative  condition. 

WHEELS 

Wheel  controls  having  been  found  thoroughly 
satisfactory  in  years  of  experience  with  automo- 
biles and  watercraf t  naturally  have  found  exten- 
sive application  to  flying  machines,  in  which  their 
advantages  of  compact  form  with  great  range  of 
movement  prove  very  valuable.  Typical  wheel 
controls  are  illustrated  in  Figures  86, 172,  202,  228, 
229,  and  250. 

LEVERS 

Lever  controls  are  almost  ideally  simple  and  in 
some  circumstances  perhaps  afford  less  chance  for 
an  operator  to  become  confused,  by  their  quality 
of  obviously  indicating  their  position.  Levers  are 
used  to  the  exclusion  of  wheels  by  the  Wrights, 
and  have  been  employed  with  considerable  success 
by  the  Voisins,  Farman,  Pelterie,  and  others  (see 
Figures  185,  190,  248,  and  252).  Undoubtedly 
there  is  much  to  be  said  for  their  positive  action 
and  simple  and  inexpensive  construction. 


FIGURE  88. — Frame,  or  "Fuselage,"  of  New  Voisin  Biplane.  The  ingenious  use  of  wood, 
left  of  larger  section  at  the  points  of  attachment  to  the  cross  struts,  which  set  into  metal 
sockets,  and  the  rigid  diagonal  wire  bracing,  constitute  a  peculiarly  interesting  example  of 
modern  high-grade  aeroplane  construction. 


FIGURE    89.— Fuselage    of    Bolotoff    Monoplane.      In    the    finished    machine    this    frame    Is 
covered  over  with  fabric  while  the  boarded  floor  comes  beneath  the  operator's  seat,  motor,  etc. 


AEROPLANE  DETAILS  229 

PEDALS 

Except  for  the  manipulation  of  minor  devices, 
pedals  have  not  been  extensively  favored  in  aero- 
plane controlling  systems,  though  Bleriot  uses  a 
pedal  to  control  the  elevator  of  his  monoplanes 
(see  Figure  197).  Other  examples  of  foot  or  pedal 
control  appear  in  Figures  225  and  248. 

MISCELLANEOUS 

Besides  wheel,  lever,  and  pedal  controls,  there 
are  several  other  devices  that  have  been  found  of 
more  or  less  practical  utility. 

Shoulder  Forks,  embracing  the  shoulders  of  the 
operator,  as  at  d,  Figure  87,  are  used  to  some  ex- 
tent to  control  lateral  balance  by  the  natural  swing 
of  the  pilot's  body  as  the  machine  cants  to  one  side 
or  the  other.  The  most  conspicuously  successful 
example  of  the  use  of  shoulder  forks  appears  in 
the  Aerial  Experiment  Association's,  and  the  Our- 
tiss  machines  (see  Figures  228  and  229).  Prac- 
tically similar  in  its  effects  though  not  in  its  con- 
struction is  Santos-Dumont's  ingenious  control  of 
the  wing  warping  of  his  tiny  monoplane  (see 
Figure  221)  by  a  lever  engaging  with  a  short  piece 
of  tubing  sewed  into  the  back  of  his  coat. 

Body  Cradles  (see  Figure  259)  were  at  first 
employed  by  the  Wrights  as  a  means  of  wing-tip 
control  for  their  early  glider,  but  have  since  been 
given  up  by  them  and  are  not  known  to  have  been 
used  in  any  successful  flying  machine. 


230  VEHICLES  OF  THE  AIR 

FRAMING 

The  strongest  and  lightest  frame  constructions 
for  the  wings,  bodies  and  other  elements  of  aero- 
plane structures  have  so  far  followed  very  closely 
the  general  lines  suggested  in  Figures  71,  72,  73, 
74,  75,  88,  89, 101, 170, 185,  192,  193,  194,  195,  197, 
225,  and  228.  For  further  details  concerning  this 
subject  see  Chapters  11  and  12. 


CHAPTEE  FIVE 

PROPULSION 

Present-day  workers  in  aeronautics  have  almost 
without  exception  achieved  their  conspicuous  suc- 
cesses with  machines  definitely  driven  through  the 
air  by  suitable  propellers,  the  power  for  which  is 
supplied  by  light-weight  engines.  This  is  true  of 
both  heavier-than-air  and  lighter-than-air  ma- 
chines though  in  the  case  of  the  aeroplane  there  is 
much  evidence  of  mysterious  and  little-understood 
laws — upsettings  of  the  very  fundamentals  of 
established  theories  of  force  and  motion — which  in 
the  opinion  of  at  least  a  few  investigators  of  the 
highest  standing  promise  that  man  will  ultimately 
achieve  the  indefinite  gliding  flight  of  the  great 
soaring  birds.  This  question,  however,  is  one  that 
calls  for  only  casual  comment  here,  it  being  more 
fully  discussed  in  Chapters  4  and  6  (see  Pages  164 
and  169.  It  is  enough  for  the  present  purpose  to 
assume  that,  present  flying  machines  requiring  pro- 
pulsion, it  is  of  importance  to  consider  and  define 
the  best  method  of  securing  such  propulsion. 

MISCELLANEOUS  PROPELLING  DEVICES 

Though  the  screw  propeller  is  the  only  device 
that  has  come  into  extensive  use  or  met  with  any 

231 


232 


VEHICLES  OF  THE  AIR 


considerable  success  in  the  propulsion  of  aerial 
vehicles,  it  is  by  no  means  the  only  device  that 
can  be  applied  to  the  purpose.  Such  other  mechan- 
isms as  have  been  developed,  though,  are  interest- 
ing more  because  of  the  theoretical  alternatives 
they  present  rather  than  because  of  anything  prac- 
tical in  either  their  promise  of  their  performance. 
Of  the  miscellaneous  propelling  devices  that 
are  important  enough  to  be  considered  there  are 
three  chief  classes  —  reciprocating  wings  and  oars, 
paddles,  and  undulating  or  wave  surfaces. 

FEATHEEING  PADDLES 

Feathering  paddles,  in  a 
measure  like  those  used  for 
boat  propulsion,  have  been 
proposed  for  propelling  and 
lifting  flying  machines.  An 
example  of  one  for  both 
propelling  and  lifting  is  pic- 
tured in  Figure  90.  In  all 
devices  of  this  character  the 
principle  is  that  of  a 
plurality  of  surfaces  carried 
rapidly  around  in  a  revolv- 
ing structure,  within  which 
they  possess  a  secondary 
FIGURE  GO.  —  Feathering-  movement  that  causes  them 

Paddle    Flying    Machine.      By 

b     ^°  travel  flatwise  when  going 


or  rearwardly 
and  edgewise  when  traveling 

rise  edgewise  through  the  ac-  _  „  ,,  A 

tion     of     the    feathered     me-  upwardly    Or    lOrWardly.       A 

*  •* 


chanism. 


PROPULSION 


233 


simplified  modification  of  this  idea  is  the  use  of  an 
ordinary  paddle  wheel  in  a  housing,  as  shown  in 
Figure  91,  the  idea  being  that  its  exposed  portion 
at  a,  revolving  as  shown  by  the 
small  arrow,  will  produce  a  for- 
ward drive  in  the  direction  of 
the  large  arrow.  It  is  almost 
needless  to  assert  that  all  de- 
vices of  this  general  character 
so  far  built  are  heavy,  compli- 
cated and  inefficient. 


FIGURE  91. — Partially 
Housed  Paddle  Wheel. 
Proposed  for  propelling 
In  direction  of  large  ar- 
row by  effect  of  exposed 
blades  at  a. 


WAVE  SURFACES 


FIGURE  92. — Wave  Surface.     Proposed 


A  somewhat  peculiar  and  very  interesting  type 
of  propelling  or  sustaining  mechanism  is  that  sug- 
gested in  Figure  92,  in 
which  a  b  is  a  flexible 
surface,  of  length  and 
width  enough  to  pre- 
sent considerable  area, 
made  capable  of  rapid 

fjLuuitJBi   &£,. —  »vave   ounitce.      rrouuseu  i      i     j  •  i  •  j      i  t 

for  propulsion,  the  progressing  sinuosity  UnQUlatlOn    by    Suitable 
of  the  surface  o  b  being  expected  to  ef- 
fect travel  in  the  direction  of  the  arrow,  mechanism    With    the 

idea  of  causing  it  to  progress  through  the  water. 
The  almost  hopelessly  difficult  problem  of  con- 
triving durable,  reliable,  and  efficient  mechanism 
for  effecting  the  undulation  required  is  probably 
a  far  greater  bar  to  a  practical  result  than  any  de- 
fect in  principle.  A  flying  machine  in  which  this 
principle  was  involved  was  that  of  F.  W.  Breary, 
secretary  of  the  Aeronautical  Society  of  Great 
Britain  in  1879. 


234  VEHICLES  OF  THE  AIR 

RECIPROCATING  WINGS  AND  OARS 

Reciprocating  wings  being  the  mechanism  by 
which  birds,  insects  and  other  flying  animals  secure 
propulsion,  and  in  many  cases  sustention,  it  is  only 
natural  that  many  designers  should  have  expected 
to  derive  satisfactory  operation  from  copies  of 
the  mechanism  of  nature.  But,  more  because  of 
the  efficiency  of  properly  designed  air  propellers 
than  because  of  the  inefficiency  of  alternative  con- 
structions, and  because  of  the  greater  simplicity 
and  reliability  of  the  simple  rotating  device,  few 
engineers  of  real  standing  have  been  able  to  con- 
vince themselves  of  any  material  advantages  to  be 
gained  by  recourse  to  the  more-complicated  and 
less-promising  wing  propulsion.  Another  basis  of 
comparison  by  which  the  propeller  profits,  and 
which  incidentally  explains  nature's  use  of  a  type 
of  mechanism  that  man  finds  less  suited  to  his  con- 
structing abilities,  is  discussed  on  Page  25. 

One  of  the  earliest  attempts  to  produce  a  dirig- 
ible balloon  involved  the  use  of  reciprocating 
wings,  the  ascent  being  that  by  Blanchard,  on 
March  2,  1784,  from  Paris  (sec  Page  72).  These 
wings  being  worked  by  man  power,  it  is  almost 
unnecessary  to  remark  that  the  attempt  ended  in 
complete  failure. 

Both  before  and  after  the  foregoing,  hundreds 
of  investigators  have  sought  to  secure  sustention 
or  propulsion,  or  both,  from  the  action  of  recipro- 
cating wings.  Such  success  as  has  been  secured, 
however,  has  been  very  small,  though  it  is  to  be 
admitted  that  reciprocating  wings  used  merely  for 


r    '      '   • 


PROPULSION  235 

propulsion  have  usually  afforded  results  much 
superior  to  any  that  have  been  attained  in  con- 
structions intended  to  lift  as  well  as  propel  by 
the  use  of  this  type  of  mechanism. 

Undoubtedly  the  most  successful  use  on  record 
of  reciprocating  wings  was  their  employment  as 
propelling  elements  in  the  various  model  flying 
machines  built  and  flown  by  Har grave  (see  Page 
122),  which  flew  well  for  distances  limited  only  by 
the  ability  to  carry  fuel.  The  wings  used  on  the 
most  successful  of  the  Hargrave  models  were  nor- 
mally straight  and  flat,  the  curvature  and  varying 
angles  of  action  desirable  to  produce  the  best  effect 
being  had  only  to  the  extent  that  the  wings 
deformed  with  a  feathering  action  under  the  pres- 
sures and  the  inertia  effects  involved  in  the  rapid 
flapping,  thus  skulling  the  whole  machine  along 
through  the  air. 

The  highest  speed  of  reciprocation  secured  with 
the  Hargrave  machines  was  248  double  beats  a 
minute  with  a  36-inch  wing,  weighing  only  a  few 
ounces,  and  moved  through  an  arc  of  not  over  80°, 
corresponding  to  a  tip  speed  of  possibly  1300  feet 
a  minute — fully  twice  that  of  the  wings  of  any 
flying  animal,  which  Marey  and  Lendenf eld  have 
shown  move  with  remarkably  little  variation  at 
about  half  this  speed,  the  proportioning  of  wing 
length  to  rate  of  vibration  being  invariably  so 
arranged  as  to  produce  this  result.  Thus  the  bee, 
with  a  wing  length  of  about  J  inch,  makes  11,400 
beats  a  minute;  the  sparrow,  with  a  wing  length 
of  about  4  inches,  makes  720  beats  a  minute ;  and 


236  VEHICLES  OF  THE  AIR 

the  stork,  with  a  wing  length  of  27  inches,  makes 
105  beats  a  minute.  When  it  is  discovered  that 
1X11,400=2850;  4x720=2880;  and  27x105= 
2835,  at  least  a  glimmering  of  the  law  is  very  ap- 
parent. 

It  is  a  safe  generalization,  based  upon  known 
facts  of  engineering,  that  tip  speeds  materially 
higher  than  those  secured  by  Hargrave  are  not 
likely  to  be  attained  in  any  durable  reciprocating- 
wing  mechanism.  On  the  other  hand,  revolving 
propellers  are  safely  worked  at  peripheral  speeds 
of  40,000  feet  a  minute.  Even  Hargrave  has 
admitted  "that  the  screw  and  the  flapping  wings 
are  about  equally  effective  as  instruments  of  pro- 
pulsion"— despite  the  fact  that  he,  undoubtedly  the 
foremost  experimenter  with  ornithopter  propul- 
sion, tried  propellers  now  known  to  be  exceedingly 
inefficient. 

SCREW  PROPELLERS 

Clearly,  the  surfaces  of  propeller  blades  are 
directly  analogous  in  their  action  upon  the  air  to 
the  action  of  aeroplanes  traveling  in  helices  (when 
the  machine  is  traveling;  in  circles  when  it  is  still) 
of  diameter  so  small  that  there  is  more  or  less 
material  difference  in  the  circumferences  of  the 
concentric  paths  traversed  and  in  the  consequent 
relative  speeds  of  the  portions  of  the  blade  surfaces 
traversing  thfem.  These  considerations  therefore 
indicate  that  the  problems  of  propeller  design  must 
involve  all  the  complex  problems  of  ordinary  aero- 
plane supporting  surfaces  in  additon  to  other 


PROPULSION  237 

intricate  factors  introduced  by  the  elements  of 
centrifugal  force,  the  screw  form  necessary  to  con- 
form to  the  peculiar  path  of  travel,  and  the  varying 
relative  speeds  of  the  different  portions  of  the 
surfaces. 

SOME  COMPAEISONS 

Much  confusion  has  existed  in  the  past  and 
still  exists  in  the  minds  of  the  uninformed  who 
fail  to  distinguish  between  the  functions  of  air 
propellers  and  the  functions  of  similar  but  not 
analogous  mechanisms.  To  clear  away  this  confu- 
sion, it  should  be  understood  that  here  are  three 
possible  devices  of  the  same  general  appearance 
but  adapted  to  quite  different  purposes.  First  of 
these  is  the  ordinary  windmill  wheel,  designed  to 
rotate  from  the  reactions  occasioned  by  a  cylin- 
drical stream  of  air  flowing  through  its  circle  of 
rotation ;  second  is  the  revolving  fan,  which  is  theo- 
retically and  practically  the  opposite  of  the  wind- 
mill wheel,  it  being  designed  to  produce  a  current 
by,  so  to  speak,  shearing  loose  a  cylinder  of  air 
from  the  surrounding  air  and  forcing  this  cylinder 
of  air  to  flow  through  its  circle  of  rotation;  and 
third  is  the  air  propeller,  bearing  no  such  close 
relationship  to  the  other  two  devices  as  they  sus- 
tain to  each  other — an  air  propeller  being  intended 
in  a  strict  sense  neither  to  react  from  disturbed 
air  flowing  through  it  nor  to  cause  a  flow  of  air, 
its  proper  function  being  that  of  progressing  with 
its  attached  mechanisms  through  the  air  with  a 
minimum  disturbance — as  nearly  as  possible  like 


238  VEHICLES  OF  THE  AIR 

a  screw  in  a  solid  nut.  Unavoidably,  when  first 
started  or  when  traveling  slower  than  its  proper 
pitch  speed,  an  air  propeller  must  operate  as  a 
more  or  less  efficient  fan,  but  under  ideal  condi- 
tions of  proper  functioning  its  blades  will  slide 
through  their  helices  of  travel  (see  Page  239)  with 
no  disturbance  of  air  but  that  due  to  the  compres- 
sions and  neutralizing  reactions  against  their  ef- 
fective surfaces. 

ESSENTIAL  CHARACTERISTICS 

The  essential  characteristic  of  a  screw  pro- 
peller being  its  perfect  adaptation  to  travel  in  a 
helical  path,  it  follows  that  in  addition  to  conform- 
ing as  nearly  as  may  be  to  other  considerations  of 
design  it  must  also  partake  of  the  character  of  a 
true  screw,  the  elements  of  which  therefore  demand 
examination. 

If  the  path  of  a,  Figure  93,  at  the  extremity 
of  a  revolving  and  advancing  propeller  blade,  be 
described  in  the  interior  surface  of  a  hollow  cyl- 
inder its  appearance  will  be  that  of  the  solid  line 
c,  from  which  it  is  at  once  evident  that  there  are 
for  any  possible  screw  several  fundamental  fac- 
tors. One  of  these  is  the  extreme  diameter,  which 
determines  the  diameter  of  the  cylinder  of  air 
through  which  progression  is  effected;  another 
is  the  pitch,  which  is  the  amount  of  advance  per 
revolution ;  and  a  third  is  the  angle  of  blade  travel, 
which  clearly  bears  a  direct  determining  relation  to 
the  pitch  and  therefore  can  be  expressed  by  the 


PROPULSION 


239 


FIGURE  93. — Helices  of  Propeller  Travel. 
The  point  d  takes  the  course  e,  and  the 
point  a  the  course  c,  in  advancing  through 
the  air. 


percent  the  pitch  is  of  the  circumference.  Continu- 
ing the  examination,  it  develops  that  a  point  in  a 
propeller  blade,  as  at  d,  not  at  the  extremity  of  the 
blade  and  thus  com- 
pelled to  travel  the 
smaller  dotted  helix 
c,  must  nevertheless 
advance  the  same 
axial  distance  per 
revolution  as  the 
point  a,  because  the 
propeller  as  a 
whole,  including  all 
points  within  it,  is  an  inflexible  mechanical  unit,  all 
parts  of  which  must  therefore  progress  at  a  uni- 
form rate  along  the  axis  of  the  invisible  cylinder  of 

air.  But  since  e  is  (in  the 
proportions  sketched,  and 
considered  as  a  circle)  only 
one-half  the  diameter  and 
circumference  of  the  helix  c 
the  given  advance  with  only 
half  the  rotational  travel  re- 
quires that  the  angle  of 
blade  travel  at  d  must  be 
twice  that  at  a,  while  the 
angles  at  all  other  points 
along  the  blade  lengths  must  similarly  vary  in  di- 
rect proportion  with  the  varying  helices  traveled. 
This  may  be  more  apparent  in  the  end  view,  Figure 
94,  of  the  propeller  and  helices,  in  which  the  hel- 
ical paths  of  the  blades  appear  as  circles — as 


FIGURE  94. — Circles  of 
Propeller  Travel.  The 
point  d  takes  the  path  e, 
and  the  point  a  the  path 
ftc,  when  the  propeller  is 
restrained  from  advancing. 


240 


VEHICLES  OF  THE  AIR 


indeed  they  become  if  the  propeller  is  permitted 
to  revolve  while  kept  from  advancing.  In  this 
figure  the  point  a  travels  the  course  ~bc  and  the 
point  d  travels  the  course  e.  Further  to  simplify 
the  analysis,  now  let  the  circles  be  and  e,  Figure 
94,  be  represented  by  the  solid  lines  be  and  e,  Fig- 
ure 95,  in  which  each  of  these  lines  starts  from  a 
point  at  a  place  proportionate  to  the  circumference 
it  represents — e  being  only  .7  as  long  as  be — while 

i 


FIGURE  95. — Diagram  of  Propeller  Pitch.  The  base  line  representing  the 
circumference  of  the  propeller  circle,  the  different  diagonal  lines  represent 
the  angles  of  travel  of  different  blade  portions. 

the  distance  f  g  equals  the  pitch  of  the  screw. 
Obviously  now,  as  has  been  explained,  for  the  point 
d  in  the  propeller  blade  to  travel  from  f  to  g  in 
the  distance  eg  it  must  be  inclined  at  twice  the  angle 
called  for  at  a  to  make  the  distance  /  g  in  going 
the  length  of  be.  Intermediate  portions  of  the 
blades,  having  to  travel  along  circumferences  rep- 
resented by  the  infinity  of  dotted  lines  suggested 
at  h  and  i,  will  correspondingly  call  for  an  infinity 
of  angles  of  travel  corresponding  to  the  angles  of 


FIGURE  103. — Wooden   Propeller   Applied   to   Car   of   Clement   Dirigible   Balloon. 


FIGURE  104.— All-Metal  Propeller  Applied  to  Dirigible  Balloon.  This  is  a  somewhat 
unusual  construction,  involving  hub  arms  welded  to  the  rarefaction  surface  of  the  sheet-metal 
blades.  It  constitutes  an  interesting  example  of  an  attempt  to  secure  results  with  the  highest 
possible  grade  of  material  in  combination  with  a  most  modern  method  of  assembling. 


PROPULSION  241 

h  i,  giving  to  the  theoretically  correct  blade  a  grad- 
ual twist  of  blade  travel,  increasing  from  a  blade 
travel  parallel  with  the  propeller  axis  at  the  exact 
propeller  center  j  to  a  surface  traveling  at  the 
pitch  angle  at  the  propeller  tip  a. 

A  very  curious  development  in  propeller  prac- 
tise has  been  the  highly-successful  use  of  propellers 
with  "straight  pitch" — that  is,  with  blade  angles 
not  varying  from  hub  to  tip,  thus  defying  most 
theories  of  propeller  construction.  It  was  with 
such  a  propeller,  of  uniform  blade  width,  that 
Glenn  Curtiss  flew  at  Kheims,  France,  in  August, 
1909,  on  which  occasion  it  was  experimentally 
determined  that  a  scientifically  designed  and  per- 
fectly constructed  Chauviere  propeller,  such  as 
was  used  by  Bleriot  in  crossing  the  English  Chan- 
nel and  by  Farman  in  his  118-mile  flight  at  Rheims, 
materially  slowed  Curtiss'  biplane.  The  explana- 
tion possibly  is  to  be  found  in  some  not-understood 
flows  of  outer  cylinders  of  air  over  concentric 
cylinders  of  air  within  them. 

Effective  Surface  of  a  propeller  is  that  portion 
of  the  circle  swept  by  the  blades  against  which 
thrust  is  developed.  For  two  principal  reasons 
there  is  little  advantage  in  attempting  to  make 
effective  surface  of  the  whole  of  the  circle.  One 
reason  is  that  the  speeds  and  angles  of  blade  travel 
towards  the  center  of  the  circle  are  too  slow  and 
too  inclined  to  produce  material  thrust  with  any 
form  of  blade  surface  that  it  is  possible  to  devise. 
The  other  reason  is  that — the  areas  of  circles  vary- 
ing with  the  squares  of  their  diameters — very  little 


242  VEHICLES  OF  THE  AIR 

area  is  lost  in  eliminating  from  thrust  considera- 
tion considerable  portions  of  the  inner  ends  of 
the  propeller  blades.  Thus,  if  one-half  of  the  blade 
length,  from  j  to  d,  Figure  94,  is  eliminated  from 
consideration  as  thrust  surface,  three-fourths  of 
the  area  of  the  circle  a  b  c  is  still  retained — the 
circle  d  e,  swept  by  j  d,  being  only  one-fourth  the 
area  of  a  6  c,  three-fourths  of  which  is  swept  by  d  a. 
Angles  of  Blades  in  an  aerial  propeller  should 
not  be  the  same  at  given  points  as  the  correspond- 
ing angles  of  blade  travel,  though  it  has  been  a 
common  mistake  to  assume  that  they  should.  The 
reason  of  this  becomes  most  apparent  by  consid- 


FIGUBB  96.  Angle  of  Propeller-Blade  to  Angle  of  Travel.  With  the  blade 
moving  in  the  direction  of  the  large  arrow,  it  is  obvious  that  to  produce 
a  thrust  in  the  direction  of  the  small  arrow  the  blade  a  must  be  inclined  to 
the  pitch,  or  line  of  travel. 


ering  the  passage  of  a  blade  through  the  air  as 
though  it  were  an  ordinary  aeroplane  surface  mov- 
ing in  a  straight  line,  as  in  Figure  96,  in  which  a 
is  a  section  of  the  blade,  6  is  its  plane  of  rotation, 
c  is  its  pitch  or  angle  of  travel,  and  d  is  its  angle 
of  inclination  to  its  angle  of  travel.  This  nec- 
essary difference  between  blade  angle  and  angle 
of  blade  travel  has  given  rise  to  a  number  of  com- 


PROPULSION  243 

plicated  misconceptions,  chiefly  noticeable  in  the 
confusion  it  has  occasioned  in  estimates  of  propel- 
ler pitch  and  slip  (see  Page  244).  Yet  the  distinc- 
tion becomes  very  apparent  when  Figure  96  is 
tilted  so  that  c  can  be  regarded  as  a  horizontal  path 
along  which  a  is  traveling  in  the  direction  of  the 
large  arrow.  This  point  of  view  gained,  it  is  an 
obvious  absurdity  to  expect  a  to  exert  a  pull  in  the 
direction  of  the  small  arrow  unless  it  is  thus 
inclined  to  its  path  of  travel. 

The  amount  of  inclination  necessary  in  a  pro- 
peller blade  varies  just  as  it  does  in  an  aeroplane 
in  accordance  with  several  factors,  chief  among 
which  are  the  speed  of  travel,  the  width  of  blade 
section,  and  the  form  of  blade  section.  It  con- 
sequently is  a  safe  generalization  for  the  designer 
to  assume  that  the  inner  and  therefore  slower-mov- 
ing portions  of  effective  blade  surface  must  present 
greater  inclination  above  the  screw-pitch  line  than 
the  outer  and  faster-moving  portions  of  blade  sur- 
face, that  wide  surfaces  probably  require  less 
inclination  than  narrow  ones  (at  given  speeds), 
and  that  the  greater  effect  of  properly-curved  sec- 
tions can  be  approximated  with  flat  and  wrongly 
curved  surfaces  only  by  the  use  of  excessive 
inclinations,  and  then  only  at  the  cost  of  wasteful 
power  application. 

Failure  to  give  due  regard  to  the  question  of 
blade  inclination  gives  rise  to  overestimates  of  slip 
in  all  cases  when  the  pitch,  or  angle  of  blade  travel, 
is  confounded  with  the  angle  of  blade  setting.  A 
propeller  designed  with  the  blade  angle  the  same 


244  VEHICLES  OF  THE  AIR 

as  the  supposed  angle  of  blade  travel  naturally  fails 
to  operate  at  the  pitch  that  is  calculated  for  it,  with 
the  result  that  in  subsequent  trials  this  discrepancy 
beween  the  real  pitch  and  the  supposed  pitch  is  dis- 
covered, added  to  such  actual  slip  as  does  occur, 
and  the  total  set  down  as  all  slip. 

Slip  is  a  phenomenon  that  presents  itself  in  all 
mechanisms,  of  whatever  type,  in  which  it  is  sought 
to  produce  positive  movements  or  reactions  in 
fluids — liquids  or  gases — by  the  action  of  solid 
parts.  AJI  air  propeller,  for  example,  caused  to 
travel  through  an  internally-threaded  cylinder  of 
metal  would  in  fact  as  in  theory  progress  without 
slip — making  the  definite  and  invariable  advance 
demanded  by  its  pitch  for  each  revolution  or  part 
of  a  revolution  accomplished.  Working  in  its 
proper  element,  however,  a  body  of  yielding  air, 
the  amount  of  the  yield  causes  a  lagging  behind 
the  theoretical  rate  of  pitch  advance,  this  lagging 
varying  with  the  design  of  the  propeller  and  the 
conditions  of  its  operation.  Naturally  the  mini- 
mization of  slip  is  an  important  element  in  the 
problems  of  propeller  design. 

The  amount  of  slip  varies  in  different  propel- 
lers, and  at  different  speeds  of  working,  from  ten 
to  fifty  percent.  Ordinarily,  about  fifteen  percent 
slip  is  to  be  regarded  as  a  small  figure. 

FORMS  OF  SURFACES 

In  the  study  of  propeller  design,  after  more 
fundamental  questions  are  disposed  of  there  at 
once  appear  the  no  less  important  questions  con- 


PROPULSION  245 

cerning  the  details  of  propeller-blade  forms.  Evi- 
dently an  infinite  variety  of  sections  and  outlines 
are  to  be  had,  so  it  becomes  necessary  to  select  on 
as  reasonable  grounds  as  may  be  reached  the  par- 
ticular combinations  best  adapted  to  afford 
required  results.  At  the  present  time,  consid- 
ering the  state  of  aerodynamic  science,  it  is  not 
possible  to  define  positively  and  logically,  by  any 
true  scientific  methods,  the  constructions  of  the 
highest  value.  Consequently,  recourse  has  been 
had  to  more  generalized  and  tentative  methods  of 
reasoning,  supplemented  by  empirical  investigation 
— by  experiment.  As  a  result  certain  important 
facts  are  fairly  well  established — though  the  num- 
ber of  these  that  are  common  knowledge  is  pos- 
sibly less  than  is  possessed  more  or  less  in  secret 
by  several  advanced  investigators. 

Plane  Sections,  as  in  the  case  of  aeroplane  sur- 
faces, were  the  first  employed  by  early  designers 
of  air  propellers,  but  as  time  went  by  and  progress 
became  more  and  more  definite,  the  same  objections 
that  were  found  to  apply  to  flat  aeroplanes  (see 
Page  171)  were  found  also  to  apply  to  flat  pro- 
peller blades,  which  in  consequence  have  been 
discarded  by  all  but  ignorant  or  uninformed 
experimenters. 

Parabolic  Sections,  modified  or  absolute,  having 
now  become  the  most  approved  form  for  aeroplane 
surfaces  (see  Page  173)  after  years  of  unsuccess- 
ful experimentation  with  flat  surfaces  and  with 
other  curves,  also  are  coming  to  be  regarded 
(though  in  this  particular  application  perhaps  less 


246  VEHICLES  OF  THE  AIR 

well  established  as  yet)  as  the  correct  ones  for 
propeller  blades.  This  being  the  case,  the  same 
general  principles  that  have  been  found  to  apply 
in  the  design  of  sustention  surfaces  (see  Page  188) 
also  are  found  to  apply  to  the  cross  sections  of  pro- 
peller blades — with  certain  modifications  intro- 
duced by  the  necessity  for  traveling  in  the  circular 
or  helical  path,  which  most  particularly  involves 
a  more  extreme  application  of  the  principle  of  cut- 
ting back  the  front  of  the  curves  at  the  ends  of  the 
surfaces,  because  the  curved  path  and  the  centrif- 
ugal action  both  tend  to  augment  the  escape  of  air 
around  the  ends  (see  Page  189). 

Air  propellers  being  subjected  to  considerable 
loading  in  the  way  of  their  ordinary  duty,  besides 
to  enormous  centrifugal  stresses  set  up  by  their 
unavoidable  high  peripheral  speed,  it  is  commonly 
necessary  to  construct  them  with  blades  very  thick 
in  proportion  to  width.  This  difficulty,  especially 
marked  in  the  use  of  strong  but  bulky  materials, 
such  as  wood,  further  increases  the  importance  of 
discovering  and  applying  correct  and  efficient 
sections. 

Blade  Outlines  are  the  theme  of  more  dispute 
and  of  many  more  differences  of  opinion  than  pre- 
vail in  the  case  of  propeller-blade  sections.  Deduc- 
tion from  present  practise  is  informing  as  much 
in  the  tendencies  it  discloses  as  it  is  in  particular 
examples.  Of  these  tendencies  there  is  that  of 
reducing  at  least  a  third  and  often  the  inner  half 
of  each  blade  to  a  mere  arm  or  stem  of  the  blade 
surface  proper,  this  stem  being  made  stocky  and 


PROPULSION  247 

strong,  and  shaped  to  go  through  the  air  with  a 
minimum  resistance,  rather  than  to  produce  any 
measurable  thrust.  The  portion  of  the  blade 
designed  to  produce  the  thrust  is  commonly  made 
widest  at  its  middle,  the  inner  end  narrowing  into 
the  stem  and  the  outer  end  narrowing  to  the  tip. 
The  object  of  narrowing  the  tip  is  twofold — first 
because  the  tip  travels  at  the  highest  speed,  mak- 
ing a  given  area  at  this  point  perform  the  greatest 
work  (besides  which  a  wide  tip  possibly  increases 
the  skin  friction  rather  materially) ;  and  second 
because  wide  tips  greatly  add  to  the  centrifugal 
stresses  without  adding  at  all  to  the  strength  of 
the  structure.  An  increasing  minority  of  designers 
prefer  to  make  the  entire  advancing  edge  of  each 
blade  perfectly  straight — lying  along  a  radius 
drawn  from  the  center  of  rotation — contending 
that  this  form  is  beneficial  in  that  it  causes  the 
edge  to  meet  all  air  particles  at  right  angles,  with- 
out setting  up  side  flows  and  eddies  in  the  concen- 
tric zones  or  helices  of  air  through  which  the  pro- 
peller passes.  With  a  straight  advancing  edge, 
the  following  edge  of  a  blade  must  be  irregular, 
since  its  contour  alone  must  provide  for  all 
required  variations  in  width  and  area.  This  con- 
sideration causes  a  decreasing  majority  of  design- 
ers to  dissent  from  the  theory  of  the  minority,  and 
divide  differences  of  area  more  or  less  equally 
between  the  advancing  and  following  edge  contours. 
In  the  matters  of  total  and  effective  blade  area,  the 
undoubted  tendency  at  present  is  to  increase  speeds 
and  correspondingly  reduce  areas.  In  a  past  era  of 


248 


VEHICLES  OF  THE  AIR 


inefficient  multibladed  propellers  it  was  not  uncom- 
mon for  half  or  more  of  the  area  of  the  circle 
of  rotation  to  be  occupied  by  blade  width,  but  in 
modern  two-bladed,  more-efficient  propellers  the 
blade  width  often  is  as  little  as  one-tenth  or  one- 
twentieth  of  that  of  the  circle  of  rotation. 

MUTIBLADED  PROPELLERS 

It  seems  *  to  be  established  to  the  satisfaction 
of  most  modern  engineers  that  the  fewer  the  blades 
in  an  air  propeller  the  nearer  ideal  its  conditions  of 
operation — too  many  blades  tending  to  interfere 
with  one  another  by  their  close  proximity  requir- 
ing each  to  work  against  air  previously  disturbed 
by  the  blade  preceding.  The  condition  is  similar 
to  the  case  of  an  aeroplane  with  identical  advanc- 


FIQURE  97. — Advancing  and  Following  Surfaces.  Showing  the  necessity 
for  a  different  curve  and  steeper  angle  in  the  rear  wing,  that  it  may  operate 
effectively  through  air  disturbed  by  the  front  wing. 

ing  and  following  surfaces  closely  spaced  in  the 
same  plane,  as  at  a  b  and  c  d,  Figure  97,  rendering 
it  necessary  for  the  rearward  surface  to  derive  its 
sustention  from  air  to  which  a  downward  move- 
ment has  been  imparted  by  the  forward  surface. 
In  the  case  of  the  aeroplane  correction  can  be 
effected  by  making  the  rearward  surface  of  a  dif- 
ferent curve  from  that  forward  and  by  inclining  it 
at  a  greater  angle,  as  in  Figure  97,  but  this  solution 


PROPULSION  249 

obviously  is  not  applicable  to  the  equally-spaced 
propeller  surfaces,  all  of  which  are  both  advancing 
and  following  because  of  their  rotary  travel.  The 
one  other  possible  solution  of  the  problem  pre- 
sented in  Figure  97  is  to  increase  the  spacing  of 
the  blades,  which  in  a  propeller  can  be  done  only 
by  increasing  their  length  or  reducing  their 
number,  or  by  a  combination  of  these. 

A  modern  three-bladed  propeller  is  shown  in 
Figure  98  and  a  f our-bladed  construction  in  Fig- 
ure 99.  Though  used  with  some  success,  neither  of 
these  meet  the  approval  of  the  most  successful 
experimenters. 

TWO-BLADED  PROPELLERS 

Two  blades  in  a  propeller  is  the  least  number 
compatible  with  smooth  running,  as  a  one-bladed 
propeller  inevitably  must  be  badly  out  of  balance 
in  so  far  as  concerns  maintenance  of  a  fixed  cen- 
ter of  thrust — while  gyration  of  the  center  of  mass 
could  be  prevented  only  at  some  critical  speed  by 
the  altogether  unwarranted  expedient  of  a  counter- 
weight. For  these  reasons  two  blades,  oppositely 
placed  in  the  same  plane  or  other  figure  of  rotation, 
are  the  least  that  can  be  used,  and  are  generally 
preferred,  though  four-bladed  propellers  have 
some  slight  vogue  and  three-bladed  ones  are  occa- 
sionally met  with.  Modern  two-bladed  propellers 
of  successful  forms  are  illustrated  in  Figures  100, 
101, 102, 103,  and  104,  in  which  characteristic  exam- 
ples of  all  the  more  approved  constructions  are 
clearly  shown.  A  close  scrutiny  of  these  will  prove 
informing  to  the  student  of  the  subject. 


250  VEHICLES  OF  THE  AIR 

PEOPELLEE  DIAMETEES 

Mechanically  considered,  the  limiting  factor  in 
propeller  speed  is  peripheral  speed  rather  than 
rotational  speed,  since  it  is  primarily  upon  this 
that  the  centrifugal  stresses,  which  are  by  far  the 
most  severe  of  all  involved,  depend.  The  propellers 
of  practically  all  successful  aeroplanes  yet  built 
are  run  at  peripheral  speeds  of  from  12,000  to 
40,000  feet  a  minute,  with  occasional  instances  of 
speeds  of  over  50,000  feet  a  minute,  the  rotational 
speeds  being  so  adjusted  to  the  diameters  as  to 
produce  little  variation  outside  of  the  range  given. 
At  the  higher  of  the  speeds  mentioned — nearly  570 
miles  an  hour — the  centrifugal  pull  exerted  at  the 
blade  tip  is  enough  to  test  the  qualities  of  the  finest 
structural  materials  available. 

That  it  is  better  to  gain  the  permissible  periph- 
eral speeds  by  the  use  of  large-diameter  propellers 
at  low  rotational  speeds,  in  preference  to  small 
propellers  at  high  rotational  speeds,  becomes  very 
evident  with  a  little  study.  Consider,  for  example, 
the  case  of  a  portion  of  a  propeller  surface,  one 
foot  long  and  one  foot  wide,  traveling  edgewise 
around  a  thirty-foot  circumference  600  times  a 
minute— it  being  assumed  that  a  peripheral  speed 
of  18,000  feet  a  minute  is  as  high  as  it  is  consid- 
ered expedient  to  use  in  the  given  case.  With  the 
conditions  stated  the  surface  passes  any  given  point 
ten  times  a  second — often  enough  to  produce  ma- 
terial disturbance  of  the  air  worked  against.  Now 
assume  the  circumference  reduced  to  fifteen  feet 


PROPULSION  251 

by  a  corresponding  halving  of  the  propeller  di- 
ameter and  immediately  it  becomes  apparent  that 
a  doubling  of  the  rotational  speed  is  allowed  with- 
out increasing  the  peripheral.  But  with  this  done 
the  assumed  propeller  surface  passes  any  given 
point  twenty  times  a  second — twice  as  often  as 
before — with  correspondingly  reduced  assurance 
of  finding  undisturbed  air  to  work  against.  More- 
over, since  the  blade  surface  travels  the  same  dis- 
tance in  the  same  time  in  both  cases,  there  is  no 
opportunity  to  reduce  its  area  on  the  ground  of 
the  higher  rotational  speed  in  the  small  propeller. 
The  result  is  that  the  blade,  which  is  of  a  width 
only  one-thirtieth  the  length  of  its  path  in  the  large 
propellers  is  in  the  small  propeller  one-fifteenth  of 
its  length — a  condition  that  operates  directly 
against  maximum  effectiveness.  Of  course  it 
is  reasonably  to  be  urged  that  when  a  propeller 
is  progressing  through  the  air  in  its  normal  con- 
dition of  operation,  instead  of  revolving  in  a  circle 
as  when  kept  from  advancing  the  blades  travel 
separate  helical  paths,  wholly  distinct  from  one 
another.  But  these  paths  are  nevertheless  closely 
adjacent,  and  become  more  closely  adjacent  with 
every  increase  in  the  number  of  blades  and  every 
decrease  in  the  pitch.  From  these  considerations 
it  must  be  evident  that  large  diameters  and  small 
blade  numbers  reduce  the  frequency  of  the  succes- 
sive traversals  of  the  adjacent  helices,  and  conse- 
quently the  frequency  and  adjacency  of  the  air 
disturbances.  A  practical  limit  is  set,  however,  by 
the  space  that  is  occupied  by  very  large  propellers. 


252 


VEHICLES  OF  THE  AIR 


ARRANGEMENTS  OF  BLADES. 

In  considering  the  design  of  aerial  propellers 
it  at  once  becomes  evident  that  there  is  possible  a 
considerable  variety  of  blade  arrangements.  Not 
only  may  the  blades  differ  in  their  number,  in  their 
outlines,  in  their  cross  section,  in  their  pitch,  and 
in  their  angles  of  setting ;  they  may  also  differ  in 
the  angles  they  make  with  their  plane  of  rotation, 
in  their  longitudinal  placing  on  the  propeller  shaft, 
and  in  the  use  of  longitudinal  sections — from  hub 
to  tip — that  are  straight  or  curved. 

Eight- Angled  Propeller  Blades,  at  right  angles 
to  the  propeller  shaft,  as  in  A,  Figure  105,  are  the 
commonest  form.  The  advantage  of  this  construc- 
tion is  that  the  centrifugal  stress  exerts  a  direct 


Figure  105. — Straight,  Dihedral,  and  Curved  Propellers. 


pull  from  the  hub,  without  any  tendency  to  move 
the  blades  longitudinally,  parallel  with  the  axis 
of  revolution.  A  supposed  disadvantage  is  the 
radial  escape  of  air  from  the  propeller  tips,  as  sug- 
gested at  a  a,  without  helping  in  propulsion.  But 
since  such  radially-thrown  air  is  more  apparent 


PROPULSION  253 

when  the  propeller  is  kept  from  advancing,  and  is 
thus  worked  as  a  blower,  than  it  is  under  normal 
conditions  in  which  the  propeller  goes  through  the 
air  instead  of  the  air  going  through  the  propeller, 
it  probably  is  not  deserving  of  serious  considera- 
tion. In  fact  the  air  can  be  thrown  radially  with 
this  type  of  blade  arrangement  only  to  the  extent 
that  it  is  dragged  by  skin  friction  or  by  incorrect 
propeller  section,  the  first  of  which  is  probably 
not  an  effect  of  great  magnitude  and  the  second  of 
which  is  a  subject  for  improved  design. 

Dihedrally-Arranged  Propeller  Blades,  set  at 
an  angle  as  at  B,  Figure  105,  or  curved  as  at  C, 
Figure  105,  obviously  utilize  the  radially-thrown 
air  at  &  &  and  c  c  in  propulsion,  but  though  they 
utilize  it  they  must  also  increase  the  amount  of  it 
by  subjecting  the  air  behind  the  blades  to  direct 
centrifugal  action  as  well  as  to  the  mere  skin  fric- 
tion that  applies  in  A,  Figure  105.  Moreover,  they 
require  very  stiff  blades,  or  else  stay  wires  as  at 
d  d  and  e  e,  to  prevent  the  blades  from  straighten- 
ing up  under  the  powerful  centrifugal  pull.  The 
presence  of  the  wires  is  an  added  objection  in  that 
these  set  up  material  resistance  to  the  rotation, 
besides  which  they  add  the  distance  g  h  to  the 
necessary  overhang  of  the  propeller  from  the 
bearing  h. 

PROPELLER  EFFICIENCIES 

The  efficiency  of  aerial  propellers  is  a  factor  of 
the  utmost  importance  in  aeronautical  engineering 
because  of  its  relation  to  power  required,  which 
in  turn  involves  the  questions  of  engine  weight  and 


254  VEHICLES  OF  THE  AIR 

fuel  quantity,  all  of  which  finally  decide  the  pos- 
sible radius  of  travel  without  alighting.  The  meas- 
urement of  efficiency  is  theoretically  very  simple, 
though  practically  not  without  some  difficulties,  the 
essentials  being  the  thrust  developed  and  the  speed 
of  movement,  which,  when  multiplied,  give  the  foot 
pounds  utilized  per  unit  of  time.  Comparison  of 
these  with  the  horsepower  developed  affords  a 
direct  measure  of  the  efficiency.  Thus  it  has  been 
stated  that  in  the  Wright  aeroplanes  the  propellers 
produce  a  thrust  of  160  pounds  at  40  miles  an  hour 
when  driven  by  the  30-horsepower  engine.  Assum- 
ing these  figures  to  be  correct — though  that  con- 
cerning the  thrust  is  probably  overestimated — the 
speed  of  40  miles  an  hour  is  equivalent  to  3,520 
feet  a  minute.  This  multiplied  by  the  160  pounds 
requires  563,000  footpounds  a  minute,  which,  com- 
pared with  the  engine  output  of  990,000  foot- 
pounds a  minute,  indicates  an  efficiency  at  the  pro- 
pellers of  about  57%.  If  the  engine  develops  only 
25  horsepower,  as  has  been  asserted,  the  efficiency 
figures  nearly  65%.  That  these  figures  are  in- 
credibly high  will  be  appreciated  when  it  is  con- 
sidered that  they  represent  not  merely  the  pro- 
peller efficiency  but  the  combined  propeller  and 
transmission  efficiency — with  a  type  of  chain  trans- 
mission quite  wasteful  of  power. 

The  explanation  probably  is  that  so  high  a  pro- 
peller thrust  as  160  pounds  is  altogether  beyond 
what  would  be  required  to  overcome  the  resistance 
that  should  be  encountered,  and,  if  developed,  its 
necessity  is  to  be  explained  only  on  the  theory  that 


PROPULSION  255 

to  the  unavoidable  head  resistances  there  must  be 
added  a  considerable  avoidable  resistance  due  to 
the  use  of  inadequate  or  wrongly-curved  sustaining 
surfaces,  made  to  serve  only  by  being  dragged 
through  the  air  at  unduly  steep  angles  of  incidence 
to  the  path  of  movement  (see  Page  133). 

In  spite  of  the  difficulties  that  have  been  en- 
countered during  the  experimental  period  of  aero- 
dynamic science  it  has  been  long  established  that 
properly-designed  air  propellers  afford  much 
higher  efficiencies  than  ever  have  been  realized 
from  water  propellers,  it  being  a  fully  demon- 
strated and  rather  amazing  fact  that  with  a  given 
engine  power  an  aerial  propeller  on  a  boat  can  be 
made  to  afford  a  higher  thrust  than  any  known 
form  of  water  propeller  that  can  be  provided. 

The  Effects  of  Form  on  aerial  propeller  effi- 
ciencies are  very  marked,  and,  though  it  cannot  be 
said  that  the  best  forms  have  been  finally  deter- 
mined, enough  experimenting  and  testing  has  been 
done  to  disclose  the  widest  possible  differences  in 
the  efficiencies  of  the  different  blade  sections,  out- 
lines, pitches,  etc.,  that  have  been  tried. 

The  Effects  of  Rotational  Speed  on  aerial- 
propeller  efficiencies  having  been  discussed  at  some 
length  on  Page  250,  it  is  enough  to  add  here  that 
up  to  some  unknown  limit  the  more  rapidly  a  blade 
surface  travels  through  the  air  the  more  perfect 
the  reaction  from  the  stratum  of  air  behind  the 
blade,  and,  incidentally,  the  thinner  this  reactive 
stratum — a  phenomenon  that  has  important  bear- 
ings on  the  question  of  interference  between  a 


256  VEHICLES  OF  THE  AIR 

plurality  of  blades.  The  head  resistance  to  the 
blade  edges  and  the  skin  friction  on  their  surfaces 
increase  with  the  speeds — the  former  about  with 
the  square  of  the  speed  and  the  latter  probably  at 
some  much  slower  rate. 

As  a  rough  general  rule  it  can  be  stated  that 
the  power  required  to  drive  a  driven  propeller 
cubes  with  increase  in  speed,  a  doubling  of  the 
propeller  speed  doubling  the  amount  of  air  acted 
upon,  doubling  the  speed  at  which  it  is  acted  upon, 
and  doubling  the  rate  of  progress  through  the  air. 

The  Effects  of  Vehicle  Speed  upon  aerial- 
propeller  efficiencies  are  especially  marked  when 
the  relations  of  pitch,  propeller  speed,  and  vehicle 
speed  are  such  as  to  compel  an  abnormal  amount 
of  slip.  Thus,  when  the  vehicle  is  kept  from 
moving  at  all  the  slip  is  100%,  and  the  propeller 
works  as  an  air  blower,  driving  a  cylinder  of  air 
to  the  rear  at  a  rate  equivalent  to  the  propeller 
pitch  minus  its  slip  considered  as  a  blower,  not  as 
a  propeller.  If  under  this  condition  the  resistance 
of  the  cylinder  of  air  to  being  sheared  loose,  so  to 
speak,  from  the  surrounding  air,  and  compressed 
against  the  air  to  the  rear  of  it,  is  greater  than  the 
head  and  other  resistances  of  the  vehicle  at  any 
given  speed,  the  propeller  thrust  under  this  con- 
dition may  be  much  greater  than  can  be  reasonably 
expected  under  the  altogether  different  conditions 
that  prevail  when  the  propeller  is  moving  through 
the  air  instead  of  the  air  moving  through  the 
propeller. 

In  the  opinion  of  some,  failure  to  consider  these 


PROPULSION  257 

points  has  been  the  reason  for  many  unwarrant- 
edly  high  estimations  of  propeller  efficiencies,  based 
upon  tests  made  with  the  propellers  restrained 
from  movement  in  an  axial  direction  and  revolved 
in  air  possessed  of  no  movement  other  than  that 
produced  by  the  propellers  themselves.  However, 
it  is  only  fair  to  state  that  Maxim  and  others  vig- 
orously oppose  the  claim  that  there  is  enough 
difference  in  the  conditions  to  invalidate  tests 
made  of  propeller  thrust  with  the  propeller  not 
advancing. 

The  greater  thrust  that  ordinarily  can  be  se- 
cured from  propellers  restrained  from  progressing 
at  their  pitch  speed  is  one  of  the  strongest  argu- 
ments that  can  be  adduced  in  favor  of  the  heli- 
copter principle,  the  helicopter  being  intended  to 
derive  sustention  from  the  reactions  under  one 
or  more  horizontally-revolving  propellers  rising 
through  the  air  at  much  lower  speeds  than  would 
result  from  a  rate  of  progress  equivalent  to  the 
pitch  (see  Page  244). 

The  Effects  of  Skin  Friction  upon  aerial- 
propeller  efficiencies  arc  much  less  of  a  factor  than 
they  are  in  water  propellers,  being  probably  almost 
negligible,  unless  at  the  most  prodigious  speeds, 
though  there  are  a  few  authorities  who  hold  to  a 
contrary  view.  Moreover,  in  further  dissimilarity 
from  the  conditions  that  apply  to  water  propellers, 
skin  friction  is  but  little  dependent  upon  extreme 
smoothness  of  the  propeller  surfaces.  This  is  be- 
cause the  cohesion  of  the  air  is  so  low  that  only  a 
small  amount  of  energy  can  be  expended  in  sliding 


258  VEHICLES  OF  THE  AIR 

one  portion  of  it  upon  another,  even  should  it  be 
the  case  that  instead  of  the  propeller  surfaces  slid- 
ing through  the  air  they  carry  thin  air  films  with 
them,  dragged  along  by  occasion  of  more  or  less 
imperceptible  deviations  from  the  unattainable 
ideal  of  perfect  smoothness. 

Determinations  of  skin  friction  can  be  best 
made  by  revolving  at  high  speeds  flat  propeller- 
like  surfaces  without  pitch,  though  in  making  tests 
of  this  sort  it  naturally  is  most  important  that 
proper  allowance  be  made  for  the  other  resistance 
factor — the  head  resistance  of  the  edges  of  the 
surfaces. 

PEOPELLEB  PLACINGS 

The  matter  of  propeller  placing  is  one  that 
admits  of  a  considerable  variety  of  schemes,  with 
a  considerable  diversity  of  opinion  as  to  which 
scheme  is  best.  Maxim,  for  example,  opposes  the 
front-placed  " tractor  screw"  on  the  ground  that 
it  "  fails  to  take  advantage  of  air  set  in  motion  by 
the  machine  as  a  whole,  as  a  means  of  neutralizing 
some  of  the  normal  slip."  Pelterie,  on  the  other 
hand,  contends  "that  the  wake  from  the  slip  itself 
is  turned  to  better  account  with  a  tractor  screw 
because  it  creates  a  higher  efficient  velocity  of  air 
under  the  center  of  the  main  wings."  To  the 
writer — in  which  opinion  he  is  upheld  by  others — 
it  seems  probable  that  both  of  the  foregoing  views 
are  based  upon  exaggerated  estimations  of  slip, 
which  with  modern  well-designed  propellers  prob- 
ably is  very  small  at  normal  vehicle  speeds.  In 


PROPULSION  259 

this  opinion  he  is  further  borne  out  by  the  fact 
that  there  are  highly-successful  modern  aeroplanes 
of  both  the  thrust-screw  and  the  tractor-screw 
types,  though  the  only  examples  of  the  former  are 
the  Wright,  Curtiss,  Cody,  and  Farman  machines, 
now  that  the  Voisins  have  gone  over  to  the  tractor- 
screw  design.  But  that  Pelterie's  theory  is  not 
without  a  measure  of  plausibility  is  rather  inter- 
estingly suggested  in  the  starting  system  recently 
patented  by  Bleriot  (see  Figure  169). 

Single  Propellers,  being  necessarily  placed  at 
or  near  the  center  of  the  head  and  other  forward 
resistances  to  the  progress  of  an  aeroplane,  can 
under  no  conceivable  circumstances  drive  the  ma- 
chine materially  out  of  its  course,  as  is  always 
dangerously  possible  with  two  propellers  (unless 
arranged  in  tandem  on  the  same  axis)  should 
one  or  the  other  for  any  reason  become  inoperative 
and  so  fail  to  maintain  its  normal  share  of  the 
thrust.  It  was  a  condition  of  this  sort,  arising  from 
the  breakage  of  one  of  the  propellers,  which  occa- 
sioned the  first  fatal  accident  in  the  history  of 
power-driven  heavier-than-air  fliers,  in  which 
Lieutenant  Selfridge  lost  his  life  and  Orville 
Wright  was  injured. 

Plural  Propellers  are  advocated  by  a  few  be- 
cause against  the  use  of  single  propellers  there  is 
to  be  urged  the  objection  that  a  machine  is  unbal- 
anced by  the  gyroscopic  and  reaction  effects,  it 
being  evident  that  these  can  be  readily  neutralized 
by  the  use  of  two  or  more  propellers,  of  the  same 
form  and  size,  symmetrically  placed,  and  revolved 


260  VEHICLES  OF  THE  AIR 

in  opposite  directions.  That  such  effects  exist 
there  is,  of  course,  no  gainsaying,  but  the  prevail- 
ing opinion  of  the  generality  of  engineers  at  the 
present  time  is  that  their  magnitude  with  propel- 
lers ranging  from  five  to  ten  feet  in  diameter  and 
weighing  from  three  to  twenty  pounds  (with  a 
large  proportion  of  this  weight  in  the  hub),  is  too 
trifling  to  be  seriously  regarded — a  view  that  is 
experimentally  upheld  in  the  fast-increasing  num- 
bers of  single-propeller  machines.  Indeed,  the 
Wright  and  the  Cody  biplanes  (see  Figures  188 
and  202),  which  have  identical  propelling  systems, 
are  the  only  successful  twin-propeller  machines  of 
large  size  that  ever  have  been  designed  in  accord- 
ance with  this  system,  which  was  first  seriously 
applied  by  Maxim  in  his  great  multiplane,  and 
subsequently  employed  in  Langley's  flying  models. 
It  certainly  has  at  least  the  appearance  of  reason- 
ableness that  a  thin  and  narrow  propeller  blade, 
from  two  to  five  feet  long,  moving  at  high  speed 
on  one  side  of  an  aeroplane,  cannot  produce  any 
considerable  reaction  per  unit  of  area  against  a 
comparatively  broad  wing  surface  on  the  opposite 
side,  from  ten  to  twenty-five  feet  long.  To  analyze 
a  particular  case,  let  there  be  considered  the  mono- 
plane with  which  Bleriot  accomplished  the  first 
crossing  of  the  English  Channel.  In  this  machine 
the  propeller  blades  are  about  3|  feet  long  and  the 
wing  span  is  over  25  feet.  The  most  effective  speed 
of  the  propeller  is  about  1,200  revolutions  a  min- 
ute, at  which  about  25  horsepower  is  applied.  This 
amount  of  power  is  the  equivalent  of  825,000  foot 


PROPULSION  261 

pounds  a  minute,  or  688  foot  pounds  per  propeller 
revolution,  involving  that  the  two  propeller  blades 
encounter  a  maximum  possible  resistance  to  their 
rotation  of  688  divided  by  21 — the  approximate 
circumference  in  feet  of  the  propeller  circle.  This 
is  an  approximate  resistance  of  33  pounds  figured 
at  the  propeller  tips.  This  load,  extended  to  the 
wing  tips,  is  the  equivalent  of  a  trifle  over  8  pounds 
unbalanced  load  on  one  wing  end,  raising  the 
weight  supported  per  square  foot  of  area  an  aver- 
age of  1  -|  ounces  higher  on  one  wing  than  on  the 
other.  Assuming  a  normal  load  of  75  ounces  to  the 
square  foot,  which  is  very  close  to  correct,  the  addi- 
tion of  this  amount  unbalances  the  machine  to  the 
extent  that  the  weight  is  only  about  2%  higher 
on  one  side  than  on  the  other. 

Wilbur  Wright  having  asserted  that  the 
Wright  machine  can  be  flown  with  fifty  pounds  of 
unbalanced  weight  at  the  tip  of  one  wing,  while 
Santos-Dumont  has  flown  with  a  forty-pound 
weight  at  one  side  of  the  body  of  his  little  mono- 
plane, nothing  more  than  a  slightly  greater  warp- 
ing of  the  wing  on  one  side  being  necessary  to  cor- 
rect the  balance,  the  altogether  immaterial  quality 
of  the  unbalanced  reaction  from  a  single  propeller 
is  as  manifest  in  practise  as  it  is  in  theory. 

Referring  again  to  the  magnitudes  of  the  gyro- 
scopic action  from  a  single  propeller,  these  are 
dependent  wholly  upon  the  factors  of  propeller 
mass  and  speed.  With  heavy  propellers  they 
undoubtedly  might  become  a  serious  factor,  but 
with  the  light  wooden  propellers  most  favored  they; 


262  VEHICLES  OF  THE  AIR 

are  quite  as  negligible  as  the  reaction  effect.  In 
fact,  this  seems  even  to  hold  true  of  the  heavier 
propellers  of  sheet  steel,  magnalium,  and  other 
alloys,  that  are  favored  by  some  builders. 

A  very  material  addition  to  the  gyroscopic 
effect  due  to  light  propellers  is  that  due  to  com- 
paratively heavy  flywheels,  when  these  are  used. 
Thus  in  the  Wright  and  Cody  machines,  in  which 
plural  propellers  are  used  to  balance  the  gyroscopic 
and  reactive  effects,  there  must  be  introduced  a 
weight-adding  element  of  unbalance  in  the  fly- 
wheel, which  cannot  readily  be  eliminated  from  a 
power  plant  in  which  there  is  chain,  gear,  or  any 
other  than  absolutely  direct  application  of  the 
power. 

Nor  can  this  question  be  begged  by  the  asser- 
tion that  geared-down  propellers — which  therefore 
might  as  well  be  plural — are  necessary  to  secure 
the  higher  efficiencies  known  to  be  secured  with 
larger  diameters  working  over  large  areas  at  low 
rotational  speeds.  For  the  answer  is  found  in 
the  fact  that  in  any  given  cases  of  equally  sound 
designing  the  efficiency  thus  gained  at  the  propeller 
is  certain  to  be  lost  in  the  transmission — not  to 
dwell  upon  the  matters  of  greater  weight  and  com- 
plication, smaller  reliability,  and  the  entry  of 
otherwise  avoided  possibilities  of  derangement  or 
failure  of  a  type  so  dangerous  as  to  constitute  an 
ever-present  menace  in  the  use  of  machines  in 
which  this  construction  is  employed. 

Gyroscopic  action  is  possibly  most  apparent  in 
its  effect  upon  steering,  it  tending  more  or  less 


PROPULSION  263 

markedly  to  deviate  a  machine  from  a  desired 
course,  when  it  is  attempted  to  steer  it.  This  devia- 
tion is  always  in  the  direction  of  the  rotation. 
Thus,  with  a  propeller  rotating  clockwise,  as 
viewed  from  the  rear  of  the  machine,  in  steering 
to  the  right  the  prow  drops  and  in  steering  to 
the  left  the  prow  rises.  In  steering  up  the  prow 
draws  to  the  right,  while  in  steering  down  the 
prow  goes  to  the  left.  With  a  propeller  rotating 
counter-clockwise,  as  viewed  from  the  rear,  the 
movements  in  all  four  possible  cases  are  just  the 
opposite.  These  movements  have  been  elaborately 
confirmed  by  Alexander  Graham  Bell  by  experi- 


FIGDRB  106. — Effect  of  Gyroscopic  Action  of  a  Single  Propeller  on  Steering. 
With  the  directions  of  rotation  shown,  effort  to  steer  in  the  direction  of  the 
solid  arrows  results  in  deviation  in  the  direction  of  the  dotted  arrows,  to  an 
angular  extent  varying  with  the  magnitude  of  the  gyroscopic  effect.  This 
tendency  can,  of  couree,  be  allowed  for  by  a  practised  operator.  In  both  views 
the  machine  is  to  be  regarded  as  approaching  the  observer. 

ments  with  a  small  gyroscope  in  a  case.  In  the 
practical  operation  of  a  machine,  this  peculiarity 
causes  practically  no  trouble,  the  pilot  learning 
to  allow  for  it  by  always  executing  steering  move- 
ments of  an  angularity  sufficient  always  to  allow 
for  the  directional  disturbance.  These  points  will 
be  better  appreciated  from  reference  to  Figure  106. 
An  example  of  tandem  propellers,  which  may 
be  either  similarly  or  oppositely  rotated  about  the 


264  VEHICLES  OF  THE  AIR 

same  axis,  is  illustrated  in  Figure  107.  The  advan- 
tages are  few  and  the  complication  considerable. 
Location  of  Propeller  Thrust,  which,  of  course, 
centers  along  the  propeller  axis  with  a  single  pro- 
peller and  is  balanced  between  the  propellers  when 
a  plurality  is  used,  is  properly,  to  secure  sustained 
flight  from  the  thrust  or  traction,  made  coincident 
with  the  exact  center  of  the  head  and  other  resist- 
ances and  preferably  with  the  axes  of  rotation 
parallel  with  the  normals  to  the  plane  of  resistance. 
In  a  correct  design  it  would  reasonably  seem  that 
the  normal  center  of  resistance  would  be  chosen, 
but  it  has  been  demonstrated  that  neither  angular 
nor  other  deviation  is  incompatible  with  success- 
ful flight,  correction  for  the  loose  designing  being 
simply  made  by  maintaining  unsymmetrical  set- 
tings or  abnormal  angles  of  the  wing  warping  or 
balancing  devices  and  of  the  vertical  elevators  or 
rudders. 

PKOPELLER  MATEEIALS 

Of  all  the  possible  elements  in  a  flying  machine, 
an  aerial  propeller  probably  most  requires  correct 
design,  careful  construction,  and  the  highest  qual- 
ities of  materials  to  make  it  stand  up  under  the 
severe  stresses  that  are  imposed  on  these  mechan- 
isms. In  every  way  approach  to  an  ideal  result 
is  restricted  by  the  severest  limitations.  Weight, 
which  is  one  road  to  strength,  is  placed  quite  out 
of  court  by  the  tremendously  high  peripheral 
speeds  involved,  which  set  up  most  terrific  centrif- 
ugal loads.  Thickness,  permitting  hollow  and 


balloon     *?hp  ,?  den  Pr°Pellers  on  Single  Shaft,  for  the  propulsion  of  a  dirigible 

Dalloon.     These  propellers  are  driven  by  a  Gnome  engine  mounted  to  revolve  in  a  horizontal 

ie  power  is  transmitted  to  the  propeller  shafts  through  bevel  gears  in  the  housing  a 


PROPULSION  265 

built-up  constructions,  and  the  use  of  light  and 
strong  but  bulky  material,  such  as  wood,  is  objec- 
tionable in  that  it  greatly  increases  the  wasteful 
resistances  to  be  overcome.  Restriction  of  size  has 
its  limits  because  of  the  tenuity  of  the  medium 
acted  upon,  demanding  the  sweeping  over  of  large 
areas  as  the  only  possible  means  of  securing  a  req- 
uisite thrust  in  an  efficient  manner. 

Obviously,  the  inevitable  result  has  had  to  be  a 
series  of  compromises,  permitting  the  use  of  the 
best  of  such  materials  as  are  available  while 
minimizing  their  objections. 

In  all  propellers,  no  matter  what  the  material, 
it  is  most  essential  that  the  opposed  blades  accu- 
rately balance,  with  the  center  of  gravity  exactly 
at  the  center  of  rotation.  If  this  is  not  the  case, 
rotation  will  occur  about  the  center  of  gravity, 
around  which  the  proper  center  of  rotation  will 
gyrate  in  a  planetary  path,  setting  up  destructive 
vibration.  In  finishing  metal  and  wood  propellers 
the  final  finish  or  carving  must  be  done  with  the 
utmost  delicacy  if  correct  balance  is  to  be  had. 
Even  an  extra  brush  stroke  in  painting  will  throw  a 
propeller  out  of  balance,  and  the  paint  must  be  cor- 
respondingly treated  in  polishing  to  correct  its 
distribution. 

Wood,  being  easily  worked  and  in  selected  qual- 
ities exceedingly  strong  and  reliable,  is  the  pre- 
ferred material  for  most  modern  aerial  propellers. 
Though  of  course  nowhere  near  as  strong  for  a 
given  section  or  bulk  as  are  many  metals,  for  a 
given  weight  it  is  excelled  only  by  the  finest  steels 


266 


VEHICLES  OF  THE  AIR 


FIQURB  108. — Working  Drawings  of  a  Wooden  Propeller. 


PROPULSION  267 

(see  Chapter  11).  Because  of  this,  in  conjunction 
with  the  fact  that  the  only  really  severe  stresses 
on  a  propeller  are  the  centrifugal,  its  mass  works 
out  so  small  in  a  given  structure  that  it  reduces  the 
loads  even  more  materially  than  it  reduces  the 
strength  of  the  sections  that  must  sustain  them. 
This  becomes  very  evident  from  a  consideration  of 
the  propeller  described  on  Page  270  and  illustrated 
in  Figures  108  and  109. 

The  greatest  objection  to  wood  as  a  propeller 
material  is,  of  course,  its  bulk,  rendering  impera- 
tive the  use  of  blade  sections  decidedly  thicker 
than  are  most  desirable. 

The  preferred  constructions  of  wooden  pro- 
pellers involve  first  the  production  of  built-up 
blocks  from  glued  laminae  of  selected  timber,  with 
the  grain  in  the  different  layers  crossed  at  a  slight 
angle  to  prevent  splitting,  after  which  the  desired 
form  is  worked  out  with  the  use  of  templets  to 
insure  correctness  of  the  different  sections.  To 
some  extent  solid  blocks  have  been  used  for  pro- 
pellers, and  this  perhaps  is  not  bad  practise  with 
certain  woods.  In  making  built-up  blocks,  the  indi- 
vidual boards  should  be  finished  with  a  tooth  plane, 
to  provide  a  slightly-roughened  and  interlocking 
surface  that  will  promote  adhesion  of  the  glue. 
Then  the  block  should  be  clamped  under  heavy 
pressure  until  thoroughly  dried. 

The  woods  considered  most  suitable  for  pro- 
pellers are  hickory,  applewood,  maple,  birch,  Cir- 
cassian or  " French"  walnut,  ash,  and  spruce.  The 
properties  and  characteristics  of  these  materials 


268  VEHICLES  OF  THE  AIR 

are  more  fully  discussed  in  Chapter  11,  which  fully 
treats  of  this  subject. 

Typical  wooden  propellers  are  illustrated  in 
Figures  100,  102,  103,  107,  140,  188,  and  246. 

Steel,  as  the  strongest  known  structural  mate- 
rial, compared  weight  for  weight  with  others,  has 
definite  points  of  superiority  over  anything  else 
that  can  be  used,  the  chief  objection  to  it  being 
the  difficulty  and  expense  of  producing  the 
necessary  qualities  in  the  requisite  shapes. 

Two  principal  methods  of  steel-propeller  con- 
struction are  at  present  in  vogue.  In  one,  single 
sheets  of  steel  (sometimes  cast  or  sheet  metal  other 
than  steel)  are  cut  to  the  desired  outlines,  stamped 
or  bent  to  the  desired  forms,  and  then  autogene- 
ously  welded  to  steel  hub  arms  that  are  placed  on 
the  backs,  or  rarefaction  surfaces  of  the  blades. 
Such  propellers  are  shown  in  Figures  99  and  104. 
In  the  other  construction,  the  blades  are  each  made 
of  two  sheets  with  the  arm  extended  between  them 
in  the  manner  of  the  wing  bars  a  a,  in  Figures 
72,  74,  193,  and  194.  Such  propellers  are  shown 
in  Figures  98  and  101,  and  are  best  assembled  by 
autogeneous  welding  of  the  hub  arms  and  the  blade 
edges,  though  riveting  and  brazing  are  employed 
to  some  extent.  The  qualities  and  physical  charac- 
teristics of  the  steels  most  suitable  for  use  in  pro- 
pellers are  discussed  in  Chapter  11. 

Aluminum  Alloys  as  propeller  materials  have 
met  with  some  success,  when  used  to  the  exclusion 
of  other  metals  as  well  as  when  employed  simply 
for  blades  or  blade  tips,  mounted  on  steel  hub 


PROPULSION  269 

arms.  One  of  the  best  of  the  aluminum  alloys  is 
magnalium  (see  Chapter  11),  which  is  both  lighter 
and  stronger  than  pure  aluminum,  and  which  lends 
itself  readily  to  casting,  forging,  stamping,  and 
machining.  A  4-foot  propeller  of  this  material  sus- 
tained the  highest  peripheral  speed  of  which  tne 
writer  knows  in  this  field  of  engineering.  This 
speed,  reached  in  a  laboratory  test,  was  50,265  feet 
a  minute,  involving  4,000  revolutions  a  minute. 
Though  the  propeller  stood  the  test  without  flying 
to  pieces,  the  blades  warped  somewhat  out  of  shape 
at  the  higher  velocities.  This  may  have  been  due, 
however,  to  poor  design.  Everything  considered, 
ease  of  manufacture  included,  there  seems  more 
than  a  fair  prospect  that  magnalium,  cast  in  iron 
molds,  may  prove  superior  to  all  other  propeller 
materials,  not  even  excepting  wood  and  steel. 

Framing  and  Fabric— the  use  of  tubular  steel 
frames  with  fabric  coverings — is  a  combination 
construction  that  has  been  experimented  with  in 
propeller  design,  notably  in  the  case  of  the  mono- 
plane illustrated  in  Figures  141,  217,  and  218. 
Even  with  ribs  and  edgings  to  stiffen  the  fabric, 
there  is  serious  doubt  as  to  the  ability  of  this  con- 
struction to  maintain  correct  blade  surfaces  under 
the  distorting  influences  of  the  high  speeds 
required,  and  in  all  cases  of  its  trial  so  far  it  has 
subsequently  been  abandoned. 

PROPELLER  HUBS 

Propeller-hub  design  is  a  most  important  detail, 
since  through  the  hub,  necessarily  small  in  size 


270  VEHICLES  OF  THE  AIR 

and  close  to  the  shaft,  where  the  tendency  to  break 
is  greatest,  must  be  transmitted  the  entire  power 
used  for  propulsion.  With  wood  propellers  the 
usual  design  involves  a  steel  shaft  through  a  hole 
in  the  wood,  with  one  or  two  flanges  through  which 
bolts  are  passed  to  transmit  the  turning  effort,  as 
shown  in  Figures  100  and  102.  A  less  usual  design 
is  that  shown  in  Figure  118,  in  which  a  steel  hub 
and  hub  arms  are  used,  to  which  the  wooden  blades 
are  riveted.  With  propellers  entirely  of  steel 
electric  or  autogeneous  welding  offer  simple  solu- 
tions of  hub  problems.  Similarly,  magnalium 
propellers,  cast  in  one  piece,  lend  themselves 
readily  to  ideal  hub  design  in  combination  with 
inexpensive  production. 

A  very  unusual  propeller  hub  is  that  shown  in 
Figure  98,  and  another  interesting  propeller  is  that 
illustrated  in  Figure  171,  in  which  it  is  seen  that 
the  hub,  the  hub  arms,  and  the  blades  are  all  sepa- 
rately made  and  subsequently  assembled. 

A  TYPICAL  PEOPELLER 

Having  now  discussed  all  the  more  important 
and  evident  considerations  that  influence  propeller 
design  and  construction,  it  is  possible  to  conclude 
this  chapter  with  a  brief  description  of  a  typical 
propeller,  which  has  been  found  to  come  very  close 
to  realizing  the  various  ideals  and  requirements 
of  these  mechanisms,  in  so  far  as  these  ideals  are 
correct  and  the  requirements  understood.  This  is 
the  propeller  illustrated  in  Figures  108  and  109, 
which  are  reproductions  of  the  mechanical  draw- 


PROPULSION  271 

ings  and  templets,  respectively,  used  in  its  con- 
struction. This  propeller,  being  designed  to  afford 
high  efficiency  with  little  power  and  at  a  low  vehicle 
speed,  was  made  very  large  in  diameter 
in  proportion  to  its  blade  width,  and  very 
flat  in  pitch.  It  is  built  up  of  six  layers  of 
|-inch  wood  and  two  of  ^-inch  stock — 
totaling  2|-  inches.  The  two  |-inch  layers, 
nearest  the  front  surface,  which  is  the 
one  that  appears  in  the  drawing,  are 
maple  and  spruce,  respectively — the  first 
to  face  the  hub  and  afford  a  hard  surface 
against  which  to  clamp  a  flange  plate  and 
the  second  to  combine  strength  with 
lightness.  For  the  latter  reason  the  first 
two  £-inch  layers  are  also  spruce,  but  the 
third  -|~inch  layer  is  of  red  birch,  which  is 
very  resistant  to  splitting  and  which,  as 
appears  particularly  in  the  side  section, 
extends  through  the  thinner  parts  of  the 
blades,  well  towards  their  tips.  Beneath 
this  come  two  more  layers  of  spruce,  to 
secure  extreme  lightness  in  the  extreme 
tip  of  the  blade,  and  then  comes  the  final 
layer  of  maple,  chosen  partly  because  of 
its  hardness  as  a  flange  backing  but 
chiefly  for  its  quality  in  holding  up  in 
thin  and  finely  carved  edges,  such  as  ex- 


FIGURE   109.  tend  clear  along  the  rear  edge  of  the 

—  T  e  mplets  &  & 

aorD  esriurrienl  blades  and  partly  around  their  tips.    The 

wooden  inpro*  advancing  edges  are  the  straight  ones,  as 

peUer*  are  shown  in  the  end  sections,  and  the 


272  VEHICLES  OF  THE  AIR 

pitch  is  18  inches,  with  a  diameter  of  6  feet.  The 
heavy  lines  and  figures  on  the  end  sections  show 
the  corresponding  angles  at  3-inch  intervals  from 
hub  to  tip.  The  chord  angles,  or  angles  of  blade 
setting  (see  Page  242),  shown  by  the  dotted  lines 
and  the  light  figures  in  the  end  sections,  are  made 
steeper  to  calculated  extents  than  the  pitch  angles, 
and  then  a  slight  further  inclination  has  been  em- 
pirically allowed  in  certain  of  the  sections.  Close 
to  the  hub  no  attempt  is  made  to  secure  thrust,  the 
sections  here  being  designed  to  go  through  the  air 
with  as  little  resistance  as  is  consistent  with  suffi- 
cient material  to  afford  the  necessary  strength 

The  sections  of  the  effective  concavities  of  the 
blades  are  approximately  parabolic,  though  not 
exactly  so  at  right  angles  to  the  radii. 

The  normal  speed  of  rotation  is  from  1,800  to 
2,000  revolutions  a  minute,  and  the  total  weight 
is  about  52  ounces,  of  which  30  ounces  is  within  six 
inches  of  the  hub  center.  This  leaves  a  weight 
of  only  11  ounces  for  each  blade,  in  each  of  which 
fully  4  ounces  is  between  6  and  12  inches  from 
the  center,  leaving  only  7  ounces  in  the  outer  24 
inches  of  each  blade. 

The  finish  is  several  coats  of  spar  varnish  on 
a  priming  coat  of  white  shellac,  the  whole  polished 
to  a  glass  smoothness  after  being  thoroughly  dried. 


i 


FIGURE  110. — Four-Cylinder  Motor  of  Wright  Biplane.  Despite  the  remarkable  success 
made  with  this  motor,  gas-engine  experts  consider  it  of  very  crude  design,  and  much  behind 
the  best  automobile  practice.  Its  considerable  weight — 190  pounds  for  25  horsepower — renders 
it  reasonably  reliable. 


FIGURE  111. — Pump-Fed  Antoinette  Engine.  These  wonderful  motors,  one  of  which  holds 
the  world's  record  for  motor-boat  speed,  have  many  aeronautical  triumphs  to  their  credit 
and  are  in  many  respects  most  ingenious  and  advanced  engineering. 


CHAPTER  SIX 

POWER  PLANTS 

The  question  of  power  for  the  propulsion  of 
various  kinds  of  flying  machines,  both  of  the 
heavier-than-air  and  lighter-than-air  types,  is  one 
at  the  present  time  of  the  utmost  importance.  In- 
deed, it  is  a  safe  assertion  that  recent  developments 
in  aeronautics  have  been  made  possible  largely 
through  the  development  of  light-weight  motors 
that  has  been  involved  in  the  history  of  the  auto- 
mobile industry.  Equally,  it  is  undoubtedly  true 
that  a  most  serious  obstacle  in  the  way  of  immedi- 
ate further  progress  is  the  lack  of  motors  still 
lighter,  more  efficient,  and  more  reliable.  Most 
flights  so  far  made,  for  example,  have  been  brought 
to  their  ends  by  motor  failure,  though  close  to  this 
limitation  always  has  been  that  of  fuel  radius, 
which  is  directly  dependent  upon  the  matters  of 
weight  and  efficiency. 

Of  course,  it  is  rather  obvious  that  some  of  the 
best  flying  machines  of  the  present  time  might  be 
flown  with  much  heavier  motors  than  are  used  in 
them — with  motors  such  as  have  been  available  for 
even  twenty  or  thirty  years.  But  it  has  seemed 
to  be  necessary  to  apply  the  light-weight  motor 
first  as  a  means  of  working  out  the  general  details 
of  the  necessary  mechanism,  the  discovery  that 

273 


274  VEHICLES  OF  THE  AIR 

heavier  motors  could  conceivably  have  been  used 
being  therefore  an  after  development. 

While  considering  this  question  of  power,  it  is 
to  be  understood  that  (as  has  been  suggested  on 
Pages  164  and  169)  some  of  the  foremost  authori- 
ties on  aeronautics — men  whose  theoretical  attain- 
ments are  as  indisputable  as  is  their  practical 
knowledge — stoutly  contend  that  it  is  going  to  be 
possible  ultimately  to  achieve  without  power 
something  akin  to  the  indefinitely-continued  soar- 
ing flight  that  is  so  indubitably  established  in  the 
case  of  the  larger  flying  birds.  Whether  or  not 
these  prophets  are  in  any  degree  carried  away  by 
their  enthusiasm  only  time  can  tell.  But  certainly 
it  must  require  some  daring  to  deny,  in  an  age  that 
has  seen  such  upsetting  of  theories  of  matter  and 
energy  as  has  been  involved  in  the  phenomena 
of  radio-active  substances  and  in  other  recent  in- 
vestigations, that  such  flight  is  possible.  It  may 
be,  perhaps,  that  the  soaring  bird  does  derive  sus- 
tension  from  upward  currents  of  air,  caused  by 
wind  friction  over  surface  contours  or  by  ascending 
streams  of  heated  air,  but  these  hypotheses  do  not 
fit  in  with  the  views  of  many  trained  observers 
who  are  almost  unanimous  in  maintaining  that 
soaring  is  performed  by  the  birds  when  such  as- 
sumed conditions  do  not  prevail.* 

*  In  the  mountains  back  of  Santa  Barbara,  California,  the  writer 
has  witnessed  the  soaring  flight  of  the  turkey  buzzard  and  the  great 
California  vulture  under  conditions  differing  from  any  he  has  heard 
credited  to  any  other  observer,  and  more  than  any  others  leading  to  the 
conviction  that  soaring  flight  does  not  require  either  ascending  or  hori- 
zontal currents  of  air.  In  the  locality  referred  to  it  frequently  happens 
that  dense  fogs  drift  in  from  the  sea  and  lay  motionless  for  hours  with 


PO  WER  PLANTS  275 

For  further  discussion  of  this  subject,  reference 
should  be  had  to  the  article  quoted  from  Prof. 
Montgomery,  in  Chapter  4. 

In  any  case  one  thing  seems  certain — that 
present  machines  are  exceedingly  wasteful  of 
power,  losing  either  through  excessive  head  resist- 
ances or  inefficient  application  probably  nine- 
tenths  of  all  that  is  developed.  For  example,  the 
latest  Wright  machine  requires  one  horsepower 
for  the  conveyance  of  each  fifty  pounds,  whereas, 
according  to  Langley,  the  condor  carries  seventeen 
pounds  with  an  energy  output  estimated  to  be 
not  above  -^T  horsepower — 395  pounds  sustained 
per  horsepower. 

Obviously,  in  providing  suitable  engines,  ex- 
tremely light  weight  and  high  efficiency  both  must 
be  sought,  since  both  are  means  to  greater  utilities 
in  the  way  of  increased  reserve-carrying  capacity 
— directly  by  reductions  in  engine  weight  and  indi- 
rectly by  reduction  in  fuel  quantity  necessary  fo* 
given  distances  of  travel. 

The  conditions  under  which  a  flying-machine 
engine  must  operate  differ  radically  from  the  con- 
ditions applying  in  ordinary  automobile  propul- 
sion, being  even  more  severe  than  those  appertain- 
ing to  racing  automobile  engines.  For,  as  in  the 
case  of  the  latter,  an  aeronautical  engine  must  be 


so  uniform  and  well-defined  an  upper  level  that  to  an  observer  who 
climbs  the  mountains  to  above  the  fog  level  it  appears  almost  substantial 
enough  to  walk  out  upon.  Yet  adjacent  to  the  surfaces  of  these  per- 
fectly quiescent  seas  of  fog,  which  would  be  visibly  stirred  by  tbe 
faintest  breath  of  air,  the  characteristic  soaring  flight — with  iti  seem- 
ingly effortless  gaining  of  altitude,  has  been  repeatedly  observed. 


276  VEHICLES  OF  THE  AIR 

capable  of  running  for  hours  upon  hours  at  high 
speed  and  high  power  output,  in  addition  to  which 
it  must  do  this  with  a  minimum  of  attention. 
These  requirements  can  be  met  in  the  case  of  the 
commonly-used  internal-combustion  motor  only  by 
the  closest  attention  to  such  details  as  lubrication, 
cooling,  carburetion,  and  ignition.  Moreover,  any 
attempt  to  provide  reliability  and  durability  with 
insufficient  bearing  sizes  and  crude  lubrication 
systems,  as  is  often  attempted  in  automobiles  by 
the  expedient  of  building  the  engine  large  enough 
to  give  much  greater  power  than  is  normally 
demanded  from  it,  defeats  its  own  end  by  the  great 
weight  it  involves. 

The  one  feature  of  its  use  that  favors  the  flying- 
machine  engine  is  found  in  the  fact  that  little 
fluctuation  is  required  in  the  power  output  and  still 
less  fluctuation  is  demanded  in  the  rotational  speed. 

Everything  considered,  and  aside  from  the 
matter  of  weight,  the  duty  of  the  aeronautical 
motor  is  more  closely  comparable  to  that  of  a 
motor-boat  engine  than  to  the  engine  of  an  auto- 
mobile. This  comparison,  too,  affords  a  much 
clearer  idea  of  the  difficulties  to  be  sur- 
mounted, for,  while  there  are  many  automobile 
engines  that  will  deliver  a  horsepower  for  each  ten 
or  fifteen  pounds  of  weight,  there  are  very  few  that 
will  do  so  for  long-continued  runs,  especially  with- 
out much  attention.  On  the  other  hand,  the  motor- 
boat  engines,  which  are  capable  of  delivering  full 
power  for  hours  without  attention,  weigh  from 
forty  to  sixty  pounds  to  the  horsepower.  And  yet 


FIGURE  112. — Three-Cylinder,  22-Horsepo\ver  Anzani  Engine.  This  engine,  which  closely 
resembles  an  ordinary  twin  motorcycle  motor,  with  the  addition  cf  an  extra  cylinder,  is  the 
one  with  which  Bleriot  crossed  the  English  Channel.  Cooling  is  by  air  passing  around  the 
drilled-out  fins  6  &  6.  At  a  a  a  are  auxiliary  exhaust  ports. 


FIGUIIE  119. — R.  K.  p.  Ten-Cylinder  .Voter  with  Concentric  Exhaust 


and  Inlet  Valves. 


POWER  PLANTS  277 

it  is  the  capabilities  of  these  engines,  rather  than 
those  of  automobile  engines,  that  constitute  the 
ideal  towards  which  aeronautical  motors,  weighing 
from  two  to  seven  pounds  to  the  horsepower,  must 
develop. 

The  quality  of  the  final  achievement  must  be 
measured  by  weight,  efficiency,  and  capacity  to 
keep  running  without  care  or  adjustment  as  long 
as  fuel  and  lubricant  are  supplied. 

GASOLINE  ENGINES 

The  gasoline  engine  in  certain  of  its  forms  being 
the  lightest  prime  mover  known,  and  having  been 
developed  to  high  degrees  of  reliability  as  an 
element  of  motor-boat  and  automobile  mechanism, 
it  is  the  only  one  at  present  finding  any  consider- 
able amount  of  favor  or  offering  much  promise  for 
future  application  to  aerial  vehicles.  Aeronautical 
engines  using  gasoline  as  fuel  have  been  built  as 
light  as  1|-  pounds  to  the  horsepower,  and  are 
made  of  considerable  reliability  in  weights  of 
from  2|  to  7  pounds  to  the  horsepower-— the  latter 
figure  permitting  thoroughly  adequate  water  cool- 
ing and  including  the  weight  of  all  necessary 
adjuncts,  such  as  ignition  and  carbureter  equip- 
ment, flywheel,  radiator,  etc. 

MULTICYLINDEE  DESIGNS 

Multicylinder  gasoline  engines  possess  various 
manifest  advantages  over  single-cylinder  construc- 
tions. In  the  first  place,  the  more  usable  four- 


278  VEHICLES  OF  THE  AIR 

cycle  motor  giving  only  one  power  stroke  in  each 
four,  it  is  rather  necessary  to  duplicate  cylinders 
to  secure  smooth  and  uniform  rotation  without 
excessive  flywheel  provision  or  crank  balancing. 
Another  advantage  of  multicylinder  construction 
is  a  little  less  obvious,  this  being  its  effect  on 
weight.  To  explain,  assume  the  case  of  a  given 
cylinder  capable  of  developing  five  horsepower  at 
its  maximum  speed.  This  speed,  as  is  well  under- 
stood by  engineers,  is  only  secondarily  a  matter  of 
rotational  speed,  it  being  primarily  a  matter  of  the 
speed  of  piston  reciprocation.  Now  to  increase  to, 
say,  twenty  horsepower,  the  cylinder  must  be 
doubled  in  all  of  its  linear  dimensions — in  both 
bore  and  stroke.  In  accordance  with  a  well-known 
law  of  geometry,  this  cubes  the  weights  and 
volumes,  so  would  at  first  appear  to  cube  the 
power,  which  would  be  the  case  if  the  speed  of 
rotation  were  maintained.  But,  because  of  the 
piston  speed  being  the  limiting  factor,  it  is  neces- 
sary in  the  larger  engine  to  reduce  the  rotational 
speed  one-half  to  avoid  increasing  the  piston  speed. 
The  consequence  is  that  though  the  weight  is  eight 
times  as  great  as  that  of  the  smaller  cylinder,  the 
power  developed  is  only  four  times  as  great,  with 
the  result  that  the  weight  per  given  power  is 
doubled. 

On  the  other  hand,  if  instead  of  increasing  the 
dimensions  of  the  small  original  cylinder  the  policy 
be  adopted  of  duplicating  this  small  cylinder — 
ranging  four  of  them,  for  example,  along  a  single 
crankcase  and  crankshaft — then  the  power  is 


POWER  PLANTS  279 

quadrupled  with  only  a  quadrupling  in  weight, 
maintaining  the  original  advantageous  proportions 
between  weight  and  power. 

Another  advantage  of  multicylinder  construc- 
tion, resulting  from  its  use  of  small  cylinders,  is 
that  these  are  more  readily  cooled  than  large, 
especially  if  it  is  undertaken  to  cool  them  by  air. 

Of  course,  as  in  the  case  of  everything  mechan- 
ical, any  given  construction  is  rather  likely  to  be 
a  compound  of  advantages  and  disadvantages. 
Among  the  latter,  operating  against  the  multicylin- 
der engine,  is  the  fact  that  the  wall  area  of  the 
combustion  chambers  totals  a  much  greater  pro- 
portion to  the  total  combustion  chamber  volume 
than  is  the  case  with  a  single  cylinder  of  the  same 
total  capacity,  causing  greater  heat  losses  to  the 
cylinder  walls  and  consequently  increased  fuel  con- 
sumption with  reduced  efficiency,  other  things 
being  equal. 

CYLINDER  ARRANGEMENTS 

In  engines  in  which  two  or  more  cylinders  are 
used  the  problem  of  cylinder  arrangement  becomes 
rather  a  vital  one,  because  of  its  many  bearings 
upon  weight,  accessibility,  and  mechanical  and 
explosion  balance.  The  arrangements  found  most 
suited  to  aeronautical  uses  are  the  vertical, 
Y-shaped,  opposed,  revolving,  etc. 

Vertical  Cylinders,  constituting  engines  of  a 
type  common  in  automobile  practice,  have  been  to 
a  considerable  extent  favored  by  aeronautic  engi- 
neers. Characteristic  examples  of  this  type  of 


280  VEHICLES  OF  THE  AIR 

construction  are  the  four-cylinder  motors  of  the 
Wright  aeroplane,  illustrated  in  Figure  110,  and 
the  Panhard  motor  illustrated  in  Figure  115.  The 
latter  is  one  of  the  most  remarkable  examples  of 
light-weight  motor  construction  in  existence,  being 
adequately  water-cooled  and  developing  a  full  45 
horsepower,  in  spite  of  the  fact  that  its  weight  is 
only  176  pounds. 

The  chief  objection  to  vertical  cylinders,  in 
their  usual  arrangement  in  a  single  line  along  a 
crankcase,  is  that  their  use  inevitably  involves 
longer  and  heavier  crankcases  and  crankshafts 
than  are  required  by  some  other  constructions. 

Though  four  cylinders  are  commonly  favored  in 
vertical  gasoline  engines,  with  six  used  to  a  consid- 
erable extent,  there  are  many  little-recognized 
merits  in  three,  five,  and  seven-cylinder  vertical 
constructions,  the  two  latter  of  which,  particularly, 
are  in  better  mechanical  balance  than  the  six- 
cylinder  (having  five  and  seven  throws  to  their 
crankshafts,  against  only  three  in  the  six).  At 
the  same  time  sufficient  overlap  of  the  successive 
explosion  strokes  is  provided  to  afford  exceedingly 
even  torque  at  such  high  speeds  as  even  the  lowest 
required  in  aeronautical  work.  The  greatest 
objection  to  engines  of  these  odd  cylinder  numbers 
is  the  expense  of  manufacturing  suitable  crank- 
shafts. 

V-Shaped  Engines,  like  the  Antoinette  motor 
illustrated  in  Figure  111,  the  Anzani  engine  illus- 
trated in  Figure  113,  the  Renault  engine  illustrated 
in  Figure  114,  and  the  Fiat  motor  illustrated  in 


FIGURE  115. — Fiat  and  Panhard  Aeronautical  Motors.  These  are  remarkable  examples  of 
refined  construction,  the  Fiat  developing  50  horsepower  with  a  weight  of  only  110  pounds,  and 
the  Panhard  weighing  176  pounds  for  45  horsepower. 


FIGURE  116.— Darracq  and  Dutheil-Chalmers  Aeronautical  Motors.  The  Darracq— in  the 
lower  view— is  the  engine  with  which  Santos-Dumont  achieved  his  recent  successful  monoplane 
flights.  It  weighs  66  pounds  and  develops  35  horsepower.  Of  particular  interest  in  the  other 
motor  is  the  flywheel  a,  with  steel  rim  and  wire  spokes. 


POWER  PLANTS  281 

Figure  115,  permit  the  working  of  two  cylinders  on 
each  throw  of  the  crankshaft — or,  briefly,  of  four- 
cylinder  crankshafts  for  eight-cylinder  engines, 
etc.  With  proper  angles  of  cylinder  placing  and 
proper  numbers  of  cylinders,  engines  of  this  type 
can  be  made  very  light  in  weight  and  exceptionally 
perfect  in  mechanical  and  explosion  balance. 

Twin-cylinder  V-shaped  engines,  which  have 
been  much  used  for  motorcycle  propulsion,  are  in 
no  better  mechanical  balance  than  single-cylinder 
engines,  but  the  greater  frequency  of  explosions 
gives  smoother  running  and  evener  power  output. 

The  three-cylinder,  V-shaped  Anzani  engine, 
illustrated  in  Figure  112,  is  of  special  interest  as 
the  motor  with  which  Bleriot  accomplished  his 
epoch-marking  flight  across  the  English  channel. 

The  four-cylinder,  water-cooled,  V-shaped  An- 
zani engine  shown  in  Figure  113  is  of  a  type  with 
two  throws  to  the  crankshaft,  with  two  cylinders 
on  each  throw.  It  has  very  much  less  crankcase 
and  crankshaft  weight  than  ordinary  four-cylinder 
engines,  is  in  excellent  mechanical  balance,  and  in 
explosion  balance  that  is  irregular  only  to  the 
rather  immaterial  extent  involved  by  the  slight 
angular  separation  of  the  two  cylinder  rows. 

The  ten-cylinder  R.  E.  P.  engine  illustrated  in 
Figure  119  is  an  extreme  but  very  successful 
example  of  modified  V-shaped  construction. 

Opposed  Cylinders,  on  opposite  sides  of  the 
crankcase,  admit  of  perfect  explosion  and  mechan- 
ical balance  with  less  cylinders  than  will  give  any- 
thing like  an  equivalent  result  in  any  other  type 


282  VEHICLES  OF  THE  AIR 

of  construction.  In  fact,  horizontal-opposed 
motors  of  the  two-cylinder  types  illustrated  in 
Figure  116  are  in  better  mechanical  balance  than 
vertical  and  V-shaped  engines  with  more  cylin- 
ders, because  the  masses  of  pistons  and  connecting 
rods  are  in  balance  not  only  in  the  opposition  of 
their  movements  but  also  in  the  rates  of  their 
opposed  movements  at  any  given  time,  which  is 
not  the  case  with  vertical  engines,  in  which  the 
angularity  of  the  connecting  rods  causes  the  pis- 
tons to  travel  the  upper  halves  of  their  strokes  at 
speeds  materially  higher  than  those  at  which  the 
lower  halves  of  the  strokes  are  traversed. 

Revolving  Cylinders,  attached  to  a  crankcase 
that  revolves  with  them  on  a  stationary  crankshaft 
with  one  throw,  to  which  all  of  the  connecting  rods 
are  attached,  have  been  considered  rather  freakish 
but  in  many  respects  constitute  a  most  meritorious 
form  of  gasoline-engine  design.  Among  the  ad- 
vantages are  the  securing  of  a  considerable  fly- 
wheel effect  without  the  added  weight  of  the 
flywheel,  effective  air  cooling  due  to  the  rapid  pas- 
sage of  the  cylinders  through  the  air,  positive 
closing  of  the  valves  without  the  use  of  springs 
(by  taking  advantage  of  the  centrifugal  force), 
greatly  reduced  crankcase  and  crankshaft  weight, 
simplification  of  the  ignition  system,  operation  of 
all  valves  by  one  or  two  cams,  and  remarkably 
smooth  and  vibrationless  running,  even  at  high 
speeds,  due  to  the  fact  that  there  is  literally  no 
reciprocation  of  parts  in  the  absolute  sense,  the 
apparent  reciprocation  between  pistons  and  cylin- 


POWER  PLANTS 


283 


ders  being  solely  a  relative  reciprocation,  since 
both  travel  in  circular  paths,  that  of  the  pistons, 
however,  being  eccentric  by  one-half  of  the  stroke 
length  to  that  of  the  cylinders.  This  latter  point 
is  made  clear  at  Figure  117,  in  which  a,  1),  c,  d,  and 
6j  are  the  cylinders,  f, 
g,  h,  i,  and  j,  are  the 
pistons  and  fc,  Z,  m,  n, 
and  0,  are  the  connect- 
ing rods  of  a  five- 
cylinder  engine  of  this 
type.  The  pistons,  it 
will  be  noted,  revolve 
in  the  path  p  around 
the  crankpin  q  as  a 
center,  while  the  cylin- 
ders revolve  in  the 
path  r  around  the 
crankshaft  s. 

In  the  ignition  sys- 
tem no  separate  leads 
are  required  for  the  different  spark  plugs,  each  of 
which  wipes  past  a  common  contact  point  as  the 
cylinder  passes  into  firing  position.  In  a  similar 
manner  the  valve  push  rods  all  travel  over  com- 
mon non-rotating  cams. 

One  of  the  most  recent  and  best  worked-out 
designs  of  revolving-cylinder  engines  is  the  seven- 
cylinder  motor  shown  in  Figures  107  and  118. 
This  motor  develops  50  horsepower  at  1,300  revo- 
lutions per  minute  and  weighs  only  about  175 
pounds.  Its  seven  cylinders  and  the  crankcase 


117. — Diagram  of  Revolving- 
Cylinder  Motor.  Note  that  the  cylin- 
ders abode  revolve  in  the  circle  r 
around  the  crankshaft  s,  while  the 
pistons  f  ff  h  t  j  and  the  connecting 
rods  k  I  m  n  o  revolve  in  the  circle  p 
around  the  crankpin  g.  Thus  there  is 
only  a  relative  reciprocation — none 
with  relation  to  external  objects — in 
this  way  almost  eliminating  vibration. 


284  VEHICLES  OF  THE  AIR 

ring  are  machined  down  from  solid  steel  forg- 
ings  to  as  thin  as  -gV  inch. 

Miscellaneous  Arrangements  of  cylinders  have 
been  devised  in  great  variety,  the  most  noteworthy 
and  successful  being  various  systems  of  grouping 
cylinders  closely  around  a  small  crankcase,  as  in 
the  engine  illustrated  in  Figures  99  and  119.  Such 
grouping  of  course  reduces  crankcase  and  crank- 
shaft weight. 

IGNITION 

Of  the  several  systems  of  internal-combustion- 
engine  ignition  that  are  in  more  or  less  general 
use,  those  possessed  of  the  most  interest  from 
aeronautical  standpoints  are  make-and-break  igni- 
tion, with  a  working  element  passing  through  the 
cylinder  walls;  jump-spark  ignition,  with  one  or 
more  coils,  external  break  by  a  timer  or  commu- 
tator, and  sometimes  vibrator  devices  in  the  exter- 
nal circuit;  ignition  by  heat  of  compression;  hot- 
tube  ignition;  and,  possibly,  catalytic  ignition. 

Of  the  foregoing,  each  has  its  different  merits 
and  demerits,  most  of  which  have  been  pretty  well 
established  through  long  experiment  and  applica- 
tion in  automobile  engines. 

Make-and-Break  Ignition  systems  when  abso- 
lutely well  designed  are  most  reliable,  and  un- 
doubtedly tend  to  make  a  motor  work  at  its  maxi- 
mum power  output  and  efficiency,  but  with  poor 
construction  or  careless  adjusting  make-and- 
break  ignition  is  exceedingly  prone  to  a  variety  of 
troubles,  among  which  are  leakages  along  the 
bearing  surfaces  through  the  cylinder  wall,  and 


FIGURE  118. — Gnome  Revolving-Cylinder  Motor.  This  remarkable  engine,  which  is  one 
of  the  lightest  and  most  powerful  yet  built,  develops  50  horsepower  at  1,200  revolutions  a 
minute.  The  seven  cylinders  and  the  crankcase  ring  are  one  piece  of  metal,  being  machined 
down  from  a  heavy  casting.  The  advantage  of  the  revolving-cylinder  design  is  its  immunity 
from  vibration,  due  to  the  absence  of  reciprocating  parts  (the  cylinders  travel  in  a  circle 
around  the  crankshaft  and  the  pistons  in  a  circle  around  the  crankpin)  and  the  elimination 
of  the  flywheel.  This  motor  at  present  holds  the  distance  and  duration  record  of  118  miles 
in  o  hours.  The  above  picture  also  affords  an  excellent  view  of  the  Bleriot  alighting  gear. 


POWER  PLANTS 


285 


Figure    120.-— 
Magnetic  Plug. 


(with  multicylinder  engines)  a  lack  of 
synchronism  in  the  ignition  times  in  the 
different  cylinders,  due  to  uneven  wear 
of  the  operating  mechanisms.  The 
most-used  current  source  for  make-and- 
break  systems  is  the  magneto.  An  in- 
teresting and  very  successful  make-and- 
break  ignition  system  is  illustrated  in 
Figure  120,  in  which  the  break  within  the  cylinder 
is  effected  magnetically  by  the  magnetic  plug. 

A  diagram  of  a  typical  ignition  system  with 
mechanical  break  inside  the  cylinder  is  presented 
in  Figure  121. 

Jump-Spark  Ignition  involves  no  working  parts 
through  the  cylinder  walls  and  is  in  its  best  forms 
rather  more  economical  in  current  consumption 
than  make-and-break  devices — a  point  of  some 
value  when  battery  current  is  depended  upon. 
Furthermore,  a  jump-spark  ignition  system  may 
be  so  designed  as  to  involve  very 
few  mechanical  parts  requiring 
much  attention  or  adjustment. 
Its  use  of  very  high  tension  cur- 
rent— approximating  30,000  volts 
in  the  secondary  circuit — renders 
it  decidedly  subject  to  short  cir- 
cuiting from  moisture  or  undue 
proximity  of  wires  and  other  ele- 
ments. However,  in  an  aerial  vehicle  it  is  easier 
to  guard  against  short  circuiting  from  moisture 
than  it  is  in  the  case  of  the  automobile.  Designed 
with  multivibrator  coils — one  coil  for  each  cylin- 


FIGDRE  121. — Make- 
and-Break  Ignition.  By 
movement  of  the  arm 
d  the  point  c  is  caused 
to  make  and  break  con- 
tact with  the  point  a, 
of  the  insulated  plug 
6,  thus  producing  a 
spark  within  the  cylin- 
der by  current  from 
the  battery  e. 


286 


VEHICLES  OF  THE  AIR 


Figure  122. — Mechanical-Break  Jump-Spark  Ignition  System.  In  this,  the 
current  from  the  battery  e  flows  through  the  circuit  a  6,  which  is  positively 
broken  at  suitable  intervals  by  the  "snapper"  device  g.  This  induces  a  high 
tension  surge  in  the  fine  winding  of  the  coil  /,  at  the  same  moment  the  sec- 
ondary current  in  d  c  is  distributed  to  the  plug  h  in  the  cylinder  »  by  the 
distributor  f,  which  is  mounted  on  the  same  shaft  bearing  the  snapper  mech- 
anism. 

der — it  is  apt  to  be  heavy,  unreliable,  uneconomical 
in  current  consumption,  and  subject  to  serious  dis- 
turbances of  synchronism,  but  with  single-coil 
systems,  and  especially  in  those  systems  in  which 
an  exceedingly  rapid  mechan- 
ical-break device  is  substituted 
for  the  vibrator,  it  becomes  one 
of  the  best  of  all  forms  of  igni- 
tion, capable  of  running  a 
multicylinder  engine  for  many 
hours  upon  the  small  quantity 
of  current  that  is  to  be  had 
from  such  small  dry  cells  as 
are  used  in  pocket  flashlights. 
Larger  dry  cells  and  storage 
batteries  are  much  used  in  high-tension  ignition 
systems  for  automobiles,  but  a  magneto  is  superior 
to  these  current  sources  in  convenience  and  relia- 
bility, though  probably  no  magneto  system  can 


FIGURE  123.  —  Jump- 
Spark  Ignition.  Every 
time  the  primary  circuit 
is  closed  by  the  timer,  or 
commutator,  g,  current 
from  the  battery  e  ener- 
gizes the  coil  f,  and  at- 
tracts the  blade  of  the 
trembler  h.  The  conse- 
quent sudden  rupture  of 
the  primary  circuit  induces 
a  current  in  the  secondary 
circuit  of  sufficient  inten- 
sity to  make  a  spark  at  the 
gap  a  of  the  plug  6. 


POWER  PLANTS  287 

be  made  as  light  as  such  a  system  as  that  illus- 
trated in  Figure  122,  in  which  very  small  dry  cells 
are  used. 

A  Jump-Spark  Ignition  System  with  vibrator 
coil  is  illustrated  in  Figure  123. 

Hot-Tube  Ignition,  such  as  is  illustrated  in  Fig- 
ure 124,  in  which  a  is  a  hollow  tube  projecting  from 
the  cylinder  6,  and  around  which  is  kept  playing 
the  flame  c,  is  one  of  the  earliest  forms  of  internal- 
combustion  engine  ignition,  having  been  exten- 
sively used  in  the  first  automobile  en- 
gines. In  its  best  types  it  is  exceedingly 
reliable,  requiring  but  little  fuel  to  main- 
tain the  external  flame,  and  in-  FIGDRE 

i     •  i       j_i  •    i   j        t»   1  1  Ignition.      Compression    of 

VOlVing  Only  the  Weight  Of  the       a  portion  of  the  charge  in 

the    cylinder     b    Into    the 


,  ,  ,   . 

heating  lamps,  which  can  be 

made  very  light.    The  difficulty    the  fueL 

of  timing  hot-tube  ignition  is  in  a  considerable 

measure  met  in  aeronautical  practice  by  the  small 

need  for  timing,  most  aerial  vehicles  requiring 

motors  working  at  practically  constant  speeds. 

Ignition  by  Heat  of  Compression  is  a  thing  of 
the  future  rather  than  of  the  present,  though  its 
possibilities  are  strikingly  suggested  in  the  com- 
mon "preignition"  that  constitutes  so  disconcert- 
ing a  disability  with  overheated  automobile  engines 
of  present  types.  Engines  have,  however,  been 
built  and  run  for  long  periods  on  ignition  by  heat 
of  compression,  and  with  careful  designing  can  be 
made  to  function  very  satisfactorily.  The  Diesel 
engine  —  the  most  efficient  internal-combustion  en- 
gine ever  built  —  works  on  practically  this  plan. 


288  VEHICLES  OF  THE  AIR 

The  engine  illustrated  in  Figure  125  is  made  to  run 
with  preignition,  though  in  its  present  forms  elec- 
tric or  other  ignition  is  required  to  start  and  keep 
it  running  until  it  reaches  its  normal  working  tem- 
perature. Naturally,  ignition  by  heat  of  compres- 
sion is  scarcely  applicable  to  mixture-fed  engines, 
working  best  with  fuel-injection  engines. 

Catalytic  Ignition,  produced  by  the  action  of 
the  hydrocarbon  gases  of  the  fuel  upon  a  small  par- 
ticle of  platinum  black  or  similar  material  placed 
in  the  cylinder,  is  a  promising  suggestion  that  has 
hung  fire  for  a  number  of  years  in  the  automobile 
field.  Most  alluring  in  its  possibilities,  it  has  so 
far  resisted  all  serious  attempts  to  reduce  it  to 
practice,  and  the  fact  that  a  small  particle  of  plati- 
num black  can  be  brought  to  a  bright,  white-hot 
glow  by  the  action  of  hydrogen  or  any  hydrocarbon 
gas  is  so  far  more  recognized  in  the  building  of 
pocket  cigar  lighters  and  automatic  gas  jets  than 
it  is  in  the  design  of  internal-combustion  engines. 

COOLING. 

The  cooling  of  internal-combustion  aeronautical 
engines  is  very  much  of  a  problem  at  the  present 
time.  Unless  a  flying-machine  engine  is  designed 
of  a  size  to  afford  a  considerable  excess  of  power, 
which  unavoidably  involves  an  excess  of  weight, 
it  must  normally  and  continuously  be  worked  up 
very  close  to  its  maximum  capacity,  which  in  turn 
involves  much  more  severe  taxing  of  the  cooling 
system  than  is  the  case  with  automobile  engines, 
which  in  ordinary  use  are  worked  to  their  full 


POWER  PLANTS  289 

capacity  only  exceptionally.  This  has  made  the 
application  of  air  cooling  seem  even  more  difficult 
than  in  automobile  engineering,  in  which  it  is 
enough  of  a  problem  to  prevent  all  but  a  small 
minority  of  manufacturers  from  attempting  it. 

Water  Cooling  therefore  being  more  or  less  of  a 
present  necessity  that  must  be  faced  in  making 
long  runs,  the  majority  of  designers  plan  to  pro- 
vide it  in  thoroughly  serviceable  and  efficient  form, 
keeping  down  weights  by  well-considered  applica- 
tion of  principles  long  established  rather  than  by 
innovations.  Light  and  effective  centrifugal 
pumps  are  used  to  produce  rapid  circulation,  often 
in  conjunction  with  considerable  thermosyphon 
action  secured  by  very  tall  radiators;  water  jackets 
are  made  of  light  sheet  metal,  preferably  applied 
by  autogenous  welding;  and  radiators  are  of  the 
thinnest  possible  materials,  most  carefully  put 
together. 

Typical  water-cooled  engines  and  cooling  sys- 
tems are  the  Wright,  Panhard,  and  Antoinette 
power  plants,  illustrated  in  Figures  111,  115,  and 
190  and  191,  respectively.  The  first  of  these 
differs  from  common  practice  in  that  the  water  is 
boiled  and  evaporated  into  steam  in  the  cylinder 
jackets,  thus  requiring  a  true  condenser  rather 
than  a  radiator  for  its  re-use,  and  permitting  the 
whole  motor  apparatus  to  function  at  a  tempera- 
ture materially  higher  than  the  objectionably  low 
temperature  of  ordinary  water-cooled  engines. 
The  Wright  engine  is  kept  cool  by  the  tall  tubular 
radiator  a,  Figures  190  and  191,  the  water  being 
circulated  by  the  centrifugal  pump  &. 


- 


296 


VEHICLES  OF  THE  AIR 


Air  Cooling  has  the  merit  over  water  cooling 
that  it  reduces  weight,  increases  reliability,  and 
simplifies  construction,  the  only  bar  to  its  uni- 
versal use  being  the  question  of  its  effectiveness. 
In  a  flying  machine,  too,  except  in  the  case  of  the 


FIGURE  125,— A  Light-Welght  Aeronautical  Motor.  In  the  functioning  of 
this  engine,  which  is  of  the  four-cycle,  internal-combustion  type,  pure  air 
is  inspired  through  the  poppet  valve  L,  during  the  suction  stroke,  directly 
from  the  outer  atmosphere.  At  the  end  of  the  suction  stroke,  air  com- 
pressed beneath  the  piston  B  is  scavenged  into  the  cylinder  A  by  the  uncov- 
ering of  the  ports  P,  the  valve  L  remaining  open.  During  the  compression 
stroke  the  combined  volumes  of  air  continue  to  be  scavenged  out  through  L 
until  the  piston  has  made  from  one-fourth  to  one-third  of  its  travel,  at  which 
point,  L  closing,  compression  begins  and  is  carried  to  a  very  high  point  in 
the  comparatively  small  clearance  M.  Carburetion  is  by  fuel  injected  directly 
into  the  cylinder  near  the  end  of  this  stroke,  and  ignition  immediately  fol- 
lows, being  effected  by  any  suitable  means.  Also,  during  the  compression 
stroke,  air  is  inspired  beneath  the  piston  through  the  leather  clack  valve 
KK.  Well  before  the  end  of  the  explosion  stroke,  L  is  opened  by  the  cam 
mechanism  to  serve  now  as  an  exhaust  valve,  and  the  burned  gases  are  dis- 
charged through  it  directly  into  the  atmosphere,  being  aided  in  their  exit 
by  another  blast  of  pure  air  through  the  ports  P  when  these  are  uncovered  by 
the  piston.  Then,  throughout  the  exhaust  stroke,  L  remains  open.  The 
cylinder  A  is  a  rery  thin  cast-iron  shell,  with  a  reinforcing  wrapping  of  piano 
wire,  and  it  is  clamped  between  the  steel  head  O  and  the  base  F  by  a  circle 
of  bicycle  spokes  DD.  The  light  sheet-steel  connecting  rod  G  is  built  up  by 
autogenous  welding  and  is  on  annular  ball  bearings  at  the  crosshead  E  and 
the  crankpin  I,  of  the  crankshaft  H.  The  disk  piston  B  is  built  up  by 
autogenous  welding  of  a  steel  center  and  a  cast-iron  bearing  portion,  and  is 
connected  by  the  hollow  steel  piston  rod  C  to  E,  which  runs  in  the  guides 
JJ  welded  to  the  frame  NN  and  the  base  F.  The  internal  scavenging  affords 
high  efficiency  and  thorough  cooling,  but  the  engine  is,  of  course,  very  noisy 
because  of  the  direct  discharge  of  the  exhaust. 


dirigible  balloons,  there  always  is  a  good  current 
of  air  available  (for  either  air  or  water  cooling) 
without  the  necessity  for  any  fan,  the  impossibility 
of  a  slow  rate  of  travel  of  the  vehicle  assuring  this. 
Nevertheless,  to  enhance  the  effect,  in  some  of  the 
most  successful  air-cooled  aeronautic  engines  there 
are  employed  blower  schemes  to  induce  powerful 


POWER  PLANTS  291 

air  currents  of  great  volume,  as  in  the  case  of  the 
eight-cylinder,  V-shaped,  air-cooled  Renault  en- 
gine illustrated  in  Figures  98  and  114. 

A  principle  that  is  greater  in  future  promise 
than  in  present  application  is  that  of  internal  air 
cooling — cooling  the  cylinders  of  the  engine  by  the 
scavenging  action  of  considerable  quantities  of  air, 
in  excess  of  those  required  for  the  charge  volumes, 
passed  through  the  interiors  of  the  cylinders  in 
the  course  of  their  functioning.  Internal  air  cool- 
ing is  most  successfully  applied  in  conjunction 
with  fuel  injection  as  a  means  of  carbureting  the 
charges. 

An  internally-cooled,  fuel-injection,  four-cycle 
engine  patented  by  the  writer  is  shown  in  a  single- 
cylinder  construction  adapted  to  aeronautical  uses 
in  Figure  125. 

CARBURETION 

The  carburetion  of  the  liquid  fuel,  usually  gaso- 
line, necessary  for  the  common  forms  of  aero- 
nautical engines  is  very  much  of  a  problem.  The 
ordinary  carbureter  is  in  most  respects  a  non- 
positive  mechanism,  in  consequence  of  which  its 
functioning  is  attended  with  many  uncertainties 
even  in  its  application  to  automobiles.  These  un- 
certainties become  many  times  more  serious  in 
application  to  aeronautics  because  of  the  difficulty 
of  effecting  adjustment  while  at  the  same  time 
keeping  the  machine  in  operation. 

Carbureters  for  flying-machine  engines  are 
closely  similar  to  those  found  best  for  automobile 
engines. 


292 


VEHICLES  OF  THE  AIR 


In  the  automobile  field  the  general  type  of  car- 
bureter most  used  is  that  illustrated  in  Figure  126, 
in  which  the  flow  of  fuel  from  the  main  fuel  tank 
is  controlled  by  the  float  a  operating  on  the  float 
valve  6,  the  fuel  entering  the  float  chamber  c 

through  the  pipe  d. 
From  the  float  chamber 
c  the  fuel  is  drawn  by 
way  of  the  atomizing 
nozzle  e  into  a  current 
of  air  passing  through 
the  pipe  /,  this  current 
being  induced  by  the 
suction  within  the  cylin- 
ders. 

Obviously,  to  secure 
uniformly- proportioned 
fuel  it  is  necessary  that 
the  fuel  level  in  the  atomizing  nozzle  be  maintained 
fairly  constant.  Also,  for  variable-speed  engines, 
it  is  desirable  that  the  carbureter  action  be  such  as 
not  to  derange  the  mixture  materially  through  vari- 
ation in  the  suction  from  different  speeds.  With 
no  means  of  compensation,  at  higher  engine  speeds 
— and  consequent  higher  suction— the  air  flowing 
through  /  tends  to  attenuate,  or  "  wiredraw",  while 
the  quantity  of  fuel  passing  through  the  atomizing 
nozzle  increases,  thus  furnishing  a  fuel  altogether 
too  rich  for  best  results.  To  offset  this  effect  it 
is  customary  to  provide  means  of  admitting  extra 
air  into  /,  as  through  the  valve  g,  which  automati- 
cally opens  wider  and  wider  as  the  suction  in- 


FIGURE  126.  —  Carbureter.  Fuel 
from  the  tank  flows  through  the  pipe 
d  until  the  float  chamber  c  is  filled 
to  a  level  determined  by  the  rising  of 
the  float  a,  which  closes  the  valve  &. 
From  c  extends  a  pipe  terminating  in 
the  atomizing  nozzle  e,  which  is  lo- 
cated in  the  pipe  f,  through  which 
air  is  inspired  in  the  direction  of  the 
arrows  by  the  suction  of  the  engine. 
This  suction  causes  gasoline  to  spray 
from  e  in  quantities  proportionate  to 
the  force  of  the  suction,  except  that 
at  very  high  suctions  the  valve  g 
opens  and  by  thus  admitting  air  be- 
tween c  and  the  engine  prevents  the 
fuel  from  becoming  too  rich  at  high 
engine  speeds.  The  butterfly  valve  at 
h  is  the  throttle. 


POWER  PLANTS  293 

creases.  Other  means  of  arriving  at  a  similar 
result  are  admission  of  air  through  positively-con- 
trolled valves  interconnected  with  the  usual  but- 
terfly throttle  placed  as  at  h,  or  by  devices  that 
reduce  the  orifice  of  the  atomizing  nozzle  e. 

In  many  carbureters  designed  primarily  for 
automobile  use,  the  floats  and  float  chambers  are 
made  concentric  in  form,  surrounding  the  atomiz- 
ing nozzle,  the  purpose  of  this  being  to  maintain 
a  constant  level  of  fuel  in  the  atomizing  nozzle 
regardless  of  fore-and-aft  or  lateral  tilting  of  the 
vehicle.  In  a  flying  machine  this  seems  hardly 
necessary  because  longitudinal  tilting  never  under 
normal  conditions  can  exceed  the  comparatively 
flat  angles  of  gilding  or  ascending,  while  lateral 
tilting  is  compensated  for  by  the  centrifugal  force 
set  up  in  turning,  which  acts  upon  the  liquid  within 
the  float  chamber  as  well  as  upon  every  other 
element  of  the  machine. 

Because  of  the  objections  to  carbureters,  the 
use  of  positive  fuel  injection,  either  into  the  intake 
piping  or  directly  into  the  cylinders,  is  a  practise 
favored  by  several  foremost  designers.  Fuel 
injection,  besides  being  positive,  admits  of  much 
closer  regulation  than  is  possible  with  a  carbureter, 
and  because  the  injection  can  be  timed  permits  of 
high  compressions  without  preignition,  the  fuel  in- 
jection being  delayed  until  ignition  is  wanted. 

The  chief  difficulty  in  the  way  of  general 
employment  of  fuel  injection  is  that  of  commutat- 
ing  the  fuel  to  the  different  cylinders  without  the 
objectionable  scheme  of  employing  a  plurality;  of 


294  VEHICLES  OF  THE  AIR 

pumps,  one  for  each  cylinder,  which  besides  adding 
complication  will  scarcely  admit  of  such  adjust- 
ment as  to  give  exactly  uniform  results  in  all  the 
cylinders — a  difficulty,  however,  which  is  no  greater 
than  that  of  equalizing  the  intake  manifold  from 
a  carbureter  so  as  to  produce  uniform  feeding.  In 
fact,  there  is  no  means  of  carburetion  in  existence 
today  for  automobile  or  similar  liquid-fuel  engines 
that  will  insure  a  power  output  from  a  plurality 
of  cylinders  varying  less  than  from  five  to  ten 
percent  from  cylinder  to  cylinder,  as  disclosed 
directly  on  the  face  of  manograph  diagrams. 

Fuel  Pumps  of  the  most  satisfactory  forms  are 
exceedingly  simple,  involving  little  more  than  a 
brass  pump  block,  chambered  out  to  receive  a  steel 
plunger  and  provided  with  ball  check  valves  and 
the  necessary  pipe  connections. 

An  ordinary  stuffing  box,  packed  with  oil  and 
cotton  wicking  and  operated  in  an  oil  bath  is 
enough  to  prevent  leakage  even  with  the  use  of  a 
fuel  such  as  gasoline,  which  is  a  solvent  for  all  com- 
irfon  lubricants.  Soft  soap,  however,  is  in  some 
respects  preferable  as  a  packing,  and  affords  very 
good  results. 

The  proper  fitting  of  the  very  small  valves 
required,  so  that  they  will  seat  positively  and 
tightly,  takes  very  close  work,  but  is  quite  within 
the  abilities  of  any  competent  machinist. 

All  valves  in  a  fuel-injection  system  should  be 
placed  vertically,  and  extreme  care  must  be  exer- 
cised in  the  arrangement  of  piping  and  in  the 
design  of  all  cavities  to  prevent  air  locks,  the  pres- 


POWER  PLANTS 


295 


ence  of  which  will  cause  most  obscure  and  difficult 
troubles. 

A  typical  fuel  pump,  which  has  been  used  with- 
out change  for  twelve  years  on  the  Mietz  and  Weiss 


FIGURE  127. — Mietz  and  Weiss  Fuel  Pump.  The  gasoline  comes  from  the 
tank  through  the  pipe  v,  attached  by  the  coupling  u,  and  enters  the  cavity 
in  the  pump  block  s  through  the  valve  t  Its  flow  is  caused  by  the  plunger 
I,  driven  by  the  eccentric  d  through  the  strap  g,  and  retracted  by  the  spring 
in,  and  it  passes  out  through  the  valve  9  and  the  pipe  p  to  the  engine  cylin- 
der. The  stroke  of  I  is  regulated  by  the  regulator  handle  a,  mounted  on  the 
regulating  shaft  b,  which  forces  down  the  plunger-guide  sleeve  i  and  thus  re- 
tracts I  from  the  eccentric.  Priming  is  effected  by  pushing  down  on  the  pump 
handle  j,  which  is  forced  up  after  each  stroke  by  the  spring  k.  At  r  is  an 
air  cock,  to  clear  the  system  of  possible  air  locks.  A  governor  weight  f  on 
the  shaft  e  Is  used  to  control  the  speed  automatically,  the  whole  running  in 
the  frame  c. 

two-cycle  kerosene  stationary  engines,  in  one,  two, 
three,  and  four-cylinder  units,  is  illustrated  in 
Figure  127. 

The  best  steels  for  making  fuel-pump  plungers 
and  other  steel  pump  parts  are  the  high  nickel 
steels  much  employed  in  automobile-engine  valve 


296  VEHICLES  OF  THE  AIR 

construction,  and  containing  from  25%  to  35% 
nickel,  which  has  the  effect  of  making  them  almost 
non-corrosive. 

MUFFLING 

Muffling  a  gasoline  engine,  while  highly  desir- 
able and  therefore  arranged  for  in  practically  all 
automobile,  motorcycle,  and  motor  boat  engines  to 
reduce  noise,  is  in  a  measure  objectionable  from 

aeronautical    stand- 
points   because   of  its 

FIGURE     128.-Silencer.       The     gases  adding    the     Weight     of 
entering    at    a    induce    an    air    flow    in  J.T_._ 
through  the  holes  c  c,  with   the  result   1116 
that   by    the   time   the   exhaust    reaches  -.  ,-1 

the  mouth  b  it  is  contracted  by  cooling  p  0  W  6  T     DV     tHe 
to  a  comparatively  small  volume.  .    ' 

pressure  it  sets  up,  and 

tending  to  overheating  by  retarding  the  escape  of 
the  hot  gases.  Still,  as  progress  continues  it  is 
likely  that  sufficient  margins  of  power  and  weight 
will  admit  of  at  least  enough  muffling  to  dispense 
with  the  more  deafening  noise  of  the  exhaust. 

Strictly  speaking,  a  distinction  can  be  made 
between  mufflers  and  silencers,  the  former  reduc- 
ing noise  by  choking  back  and 
retarding  the  exit  of  the  gases  "s 


by  means  of  baffle  plates,  pro-     FIGURE  129.—  Mumer.   The 

.  .  TIT  i  gases  entering  at  a  flow  back 

lections,  and  chambered  con-  and  forth  as  indicated  by  the 

J  arrows   until  they   issue  from 

structions,  while  silencers  re-  tne  vent  6- 

duce  noise  not  so  much  by  retarding  the  exhaust 

as  they  do  by  cooling  and  thus  shrinking  the  gases. 

The  latter  plan  is  by  all  means  the  most  advantage- 

ous in  designing  for  minimums  of  weight  and  back 

pressure. 

The  lightest  form  of  silencer  is  a  long,  fun- 


POWER  PLANTS  297 

nel-shaped  tube,  such  as  is  illustrated  in  Figure 
128,  in  which  a  is  the  exhaust  pipe  from  the  engine, 
&  is  the  mouth  of  the  silencer,  and  c  c  are  openings 
into  which  air  is  drawn  by  the  blast  at  d,  this 
induced  air  assisting  cooling.  A  typical  muffler  is 
illustrated  in  Figure  129.  A  modification  of  this 
type  into  a  combined  muffler  and  heater  is 
illustrated  in  Figure  255. 

AUXILIARY  EXHAUSTS 

Auxiliary  exhaust  ports,  as  at  a  a  a,  Figure  112, 
arranged  to  be  uncovered  by  the  piston  just  as  it 
reaches  the  bottom  of  its  stroke,  greatly  assist  cool- 
ing, especially  of  the  exhaust  valve,  and  add  mate- 
rially to  power  by  conducing  to  free  escape  of  the 
burned  charge.  The  auxiliary  exhaust  is  much 
used  in  racing-motorcycle  and  air-cooled  automo- 
bile engines. 

FLYWHEELS 

Flywheels  or  some  equivalent  are  necessary  in 
all  forms  of  internal-combustion  engines  to  pro- 
duce uniform  rotation  and  torque  from  the  inter- 
mittent impulses  in  the  different  cylinders.  Con- 
sequently it  is  a  general  rule  that  the  fewer  the 
cylinders  the  greater  the  flywheel  effect  required. 

Since  the  momentum  of  a  flywheel  is  a  function 
not  only  of  its  mass,  but  also  of  the  velocity  at 
which  this  mass  moves,  increased  flywheel  effect 
can  be  secured  either  by  adding  more  material 
or  by  increasing  size.  The  latter  when  permissible 
is  much  the  more  advantageous  plan,  because,  for 
example,  doubling  the  diameter  of  a  flywheel — sim- 


298  VEHICLES  OF  THE  AIR 

ply  redistributing  the  material — quadruples  the 
effect,  since  the  resulting  doubling  of  the  circum- 
ference doubles  peripheral  speed  while  at  the  same 
time  the  rim  is  removed  to  twice  the  distance  from 
the  center.  On  the  other  hand,  simply  adding  lat- 
erally to  a  flywheel  another  of  similar  size  and 
weight  is  doubling  of  the  weight  with  only 
doubling  of  the  flywheel  effect. 

From  these  considerations  it  will  be  understood 
that  the  larger  a  flywheel  the  better,  the  only  limits 
being  those  set  up  by  consideration  of  space  avail- 
able and  the  matter  of  interference  with  the  details 
of  surrounding  mechanism. 

It  being  settled  as  desirable  that  as  much  as 
possible  of  the  weight  of  a  flywheel  be  concentrated 
in  its  rim,  where  the  speed  of  movement  is  highest, 
the  tendency  in  designing  flywheels  for  aeronaut- 
ical engines  is  to  reduce  the  centers  of  these  wheels 
to  their  lowest  terms. 

A  very  interesting  design  is  that  illustrated  at 
a,  Figure  116,  in  which  the  rim  is  seen  to  be  of 
turned  steel,  held  to  its  hub  by  such  an  arrange- 
ment of  stout  wire  spokes  as  is  used  in  an  ordinary 
bicycle  wheel. 

As  is  explained  in  a  previous  paragraph  (see 
Page  282),  the  use  of  revolving  cylinders  in  an 
engine  eliminates  the  necessity  for  a  flywheel. 
Another  road  to  the  elimination  of  the  flywheel, 
with  its  undesirable  added  weight,  is  the  use  of 
propellers  as  a  substitute  for  it — a  perfectly  feas- 
ible and  very  usual  plan  when  the  design  is  such 
that  the  propeller  or  propellers  can  be  mounted 


POWER  PLANTS  299 

directly  on  a  prolongation  of  the  engine  crank- 
shaft. It  will  be  noted  that  this  construction  is 
employed  in  several  of  the  aeroplanes  illustrated 
herein. 

STEAM  ENGINES 

The  steam  engine,  though  not  extensively 
applied  either  to  automobile  propulsion  or  to  aero- 
nautics, nevertheless  has  disclosed  very  definite 
merits  in  so  far  as  it  has  been  applied.  Not  the 
least  of  the  advantages  of  a  steam  power  plant  is 
the  ability  to  use — in  one  and  the  same  plant — 
a  great  variety  of  common  fuels,  readily  obtainable 
anywhere. 

In  the  matter  of  weight,  one  of  the  lightest 
engines  of  any  kind  ever  built  was  that  exhibited 
by  Stringf  ellow  at  the  British  Aeronautical  Exhibi- 
tion in  1868  (see  Page  157),  this  engine  develop- 
ing one  horsepower  for  each  thirteen  pounds  of 
weight. 

In  1892  Laurence  Hargrave  built  a  steam 
engine  weighing  only  5  pounds,  11  ounces,  with 
boiler,  and  showed  how  the  boiler  could  be  light- 
ened enough  to  bring  the  weight  down  to  only  3 
pounds,  14  ounces  without  reducing  the  output  of 
.653  horsepower.  This  figures  less  than  6  pounds 
per  horsepower  (see  Page  122). 

A  larger  light  engine  was  that  designed  by 
Clement  Ader,  for  use  in  his  early  aeroplane  expe- 
riments (see  Page  134).  This  engine,  which  was 
in  duplicate — one  for  each  of  the  two  propellers — 
had  two  high  and  two  low-pressure  cylinders  in 
each  unit,  placed  horizontally,  and  with  the  bores 


300  VEHICLES  OF  THE  AIR 

2.56  inches  and  3.937  inches  and  the  stroke  3.937 
inches.  The  boiler  was  of  the  multitubular  type, 
alcohol-fired,  and  delivered  steam  at  a  pressure  of 
140  pounds  to  the  square  inch.  The  two  motors 
together,  without  boiler,  weighed  slightly  over 
92J  pounds  and  ran  at  600  revolutions  a  minute. 

A  particularly  remarkable  engine  was  that 
designed  by  Hiram  Maxim  and  used  in  his  experi- 
ments in  1894.  This  engine,  which  was  in  the 
machine  illustrated  in  Figures  235  and  236, 
weighed  with  the  boiler  but  without  water  about 
1,800  pounds,  and  developed  363  horsepower — less 
than  five  pounds  to  the  horsepower. 

Another  very  light  aeronautical  engine  was  the 
steam  engine  used  by  Professor  Langley  in  his  suc- 
cessful model  flying  machine,  which  flew  over  the 
Potomac '  River  in  1896  (see  Page  136).  This 
power  plant,  with  a  total  weight  of  8  pounds, 
developed  1J  horsepower. 

In  the  matter  of  reliability,  it  is  a  well  known 
fact  that  several  automobiles  with  steam  power 
plants,  besides  being  substantially  as  light  as  the 
best  gasoline  cars  of  similar  capacity  are  well  above 
the  average  in  reliability  and  durability,  though  it 
often  is  charged  against  them  that  they  require 
unusually  expert  care  and  handling,  a  requirement 
that  for  the  time  being  is  not  an  especial  objection 
in  the  case  of  the  flying  machine. 

A  steam  engine  recently  designed  in  France  for 
application  to  an  aeroplane  is  that  illustrated  in 
Figure  130,  the  boiler  for  supplying  it  with  steam 
being  shown  in  Figure  132. 


FIGURE  130. — Steam  Engine  for  Aeronautical  Use.  This  engine,  which  is  of  French 
design,  follows  gasoline-engine  practice  in  the  V-placing  of  the  cylinders  and  the  use  of  poppet 
valves.  It  is  designed  for  use  with  the'  boiler  shown  below. 


FIGURE  132. — Water-Tube  Boiler  for  Aeronautical  Use.  This  boiler  closely  resembles  the 
steam  "generators"  used  in  steam  automobiles.  Its  light  weight,  efficiency,  capacity  for  the 
rapid  production  of  steam  at  extremely  high  pressure,  and  its  freedom  from  scaling  and 
corrosion  are  the  chief  merits  of  this  construction. 


POWER  PLANTS  301 

AVAILABLE  TYPES 

Of  the  different  types  of  steam  engines  those 
most  available  for  aeronautical  service  are,  unfor- 
tunately, in  most  cases  the  least  efficient — a  diffi- 
culty that  applies  in  practically  similar  degree  to 
internal-combustion  engines.  Thus  the  elaborate 
compound,  triple,  and  quadruple  expansion  types, 
by  which  a  maximum  of  the  available  energy  of 
the  fuel  is  transformed  into  useful  work,  involve 
too  great  a  weight  of  machinery  to  permit  their  use. 
Instead  of  these  the  less-efficient,  light,  high-speed 
and  high-pressure  single-acting  and  double-acting 
engines  are  found  best,  though  the  amount  of  com- 
pounding that  has  been  found  permissible  in 
automobile  engines  is  perhaps  worth  securing. 

The  steam  turbine  would  appear  on  first  con- 
sideration to  be  the  best  possible  type  of  motor 
for  a  flying  machine,  its  direct  rotary  movement 
permitting  a  minimum  loss  in  the  transmission  of 
the  power  to  the  evenly-revolving  propellers,  but 
it  is  an  unfortunate  fact  that  at  present  steam 
turbines  in  any  but  the  largest  size  are  woefully 
inefficient.  With  future  developments  in  this 
department  of  steam  engineering,  together  with 
probable  decrease  in  the  size  of  flying  machines,  it 
seems  more  than  likely  that  the  moderate  size  steam 
turbine  may  here  come  into  its  own. 

BOILEES 

Steam  boilers  are  of  two  principal  types — ^fire- 
tube  and  water-tube.  Typical  of  the  former  is  the 
common  flue  boiler  illustrated  in  Figure  131,  in 


302 


VEHICLES  OF  THE  AIR 


which  a  a  are  copper  tubes  headed  into  the  steel 
crown  sheets  6  and  c,  which  are  further  connected 
by  the  steel  shell  d,  wrapped  with  piano  wire  to 
afford  the  necessary  strength  with  extreme  light- 
ness. This  type  of  boiler  has  been 
much  used  in  steam  automobiles 
and  is  very  light  and  efficient,  the 
hot  gases  from  the  fire  beneath  it 
passing  through  the  flues  and  thus 
c  coming  into  contact  with  very  ex- 
tensive surfaces  on  the  other  side 
of  which  is  the  water  to  be  heated. 
t7p/luol  ^  flash  "generator",  which 
8eh°enetl88t6  ef  dn?  has  been  f  ound  most  successful  in 


nected     by     the     tubes  .  ,   .-,  ,  .  .    ,       n 

ooo,  through  which  automobile  practise,  consists  lun- 

the  fire  is  forced.     The  r 


.  __ 

di?nSf  wfreTrapped  damentally  01  one  or  more  long 
steel  tubes  more  or  less  closely 
coiled  through  the  fire,  and  provided  with  means 
for  pumping  water  into  one  end,  to  issue  as  steam 
at  the  other.  A  boiler  of  this  type  naturally  must 
be  made  to  stand  a  high  temperature  without  in- 
jury, regardless  of  whether  or  not  it  contains 
water,  the  water  being  pumped  in  only  as  steam 
is  required  and  being  "flashed"  into  steam  as  it 
comes  in  contact  with  the  hot  surfaces.  The  best 
examples  of  this  type  of  boiler  are  remarkably 
light  and  efficient,  will  withstand  working  pres- 
sures up  to  1,200  pounds  to  the  square  inch,  and  are 
immune  from  the  explosion  possibilities  that  al- 
ways exist  in  connection  with  other  types,  espe- 
cially if  very  high  pressures  are  employed. 

A  flash  generator  designed  to  supply  steam  for 


POWER  PLANTS  303 

the  aeronautical  engine  shown  in  Figure  130  is 
illustrated  in  Figure  132. 

BURNERS 

Burners  for  steam  power  plants  vary  from  the 
common  automobile  type  gasoline  burner  to  the 
numerous  types  of  grates  and  fireboxes  required 
for  coal,  wood,  and  other  heavy  fuels.  For  aero- 
nautical steam  power  plants  there  would  appear  to 
be  the  widest  field  for  a  combination  firebox, 
capable  of  being  readily  arranged  to  consume 
either  liquid  or  solid  fuel.  This  should  not  involve 
any  serious  weight  or  complication,  while  the  al- 
most unvarying  power  demand  makes  possible 
utilization  of  solid  fuels  with  much  less  attention 
than  would  be  necessary  with  an  automobile. 

FUELS 

Of  the  fuels  available  for  steam  power  plants, 
the  most  easily  fed  and  controlled  are  the  liquid 
fuels,  such  as  gasoline,  kerosene,  benzene,  benzine, 
alcohol,  and  crude  petroleum. 

Of  the  solid  fuels  there  are  coal,  coke,  briquettes 
(of  coal  dust,  pitch,  and  other  materials),  char- 
coal, and  wood.  Coke  and  charcoal  afford  very 
clean  and  hot  fires  with  little  or  no  smoke.  Wood 
has  the  merit  of  universal  availability,  so  that  a 
machine  utilizing  it  could  find  fuel  by  descending 
in  almost  any  locality.  Something  of  the  same  sort 
is  true  in  lesser  degree  of  coal.  The  weights,  bulks, 
and  heating  value  of  the  more  common  liquid  and 
solid  fuels  are  given  in  the  following  table: 


304 


VEHICLES  OF  THE  AIR 


COMPARISON  OP  FUELS 


WEIGHT 

CALORIFIC  VALUE 

FUEL 

(per  cubic  ft.or  gallon) 

(In  British  Thermal 
Units  per  Pound) 

6.16  pounds 

18000—21900 

Denatured  Alcohol       .                   . 

14172 

22000 

Distillate  

7  30  pounds 

18000 

Crude  Petroleum         .                      . 

7  35  pounds 

20500 

*  LiQue  fied  Acetylene  

4.00  pounds 

18260 

Anthracite  Coal      

83  to  110  pounds 

15225 

80  to  89  pounds 

15370 

Coke  

80  to  40  pounds 

13620 

Charcoal                  

10  to  12  pounds 

13500 

7000 

*  Acetylene  liquefied  at  68°  F.  under  597  pounds  to  the  square  Inch.  In 
this  form  it  is  very  dangerous  unless  its  use  is  attended  by  proper  precau- 
tions, but  it  is  nevertheless  considered  by  some  engineers  to  posses  important 
possibilities  in  applications  to  light-weight,  high-power  engines. 

Of  even  more  importance  than  its  theoretical 
calorific  value  is  the  efficiency  with  which  a  fuel 
can  be  utilized  in  a  practical  engine.  Thus  alcohol, 
with  a  comparatively  low  thermal  value,  can  be 
utilized  with  a  high  thermal  efficiency,  in  internal- 
combustion  engines  giving  fully  as  much  power  as 
equivalent  weights  of  gasoline. 

ELECTRICITY 

Though  electrical  power  for  the  propulsion  of 
aerial  vehicles  has  too  many  shortcomings  to  admit 
of  its  present  practical  utilization,  it  undoubtedly 
holds  out  a  few  promises  that,  though  vague,  make 
it  worthy  of  some  consideration. 

ELECTRIC  MOTOES 

Electric  motors,  while  ideal  for  aeronautical 
application  to  the  extent  that  they  permit  great 
speeds  and  develop  their  power  through  directly- 
rotating  elements,  are  decidedly  heavy — even  with- 
out considering  the  question  of  current  source — as 


POWER  PLANTS  305 

compared  with  most  other  prime  movers.  The 
lightest  and  highest  speed  electric  motor  ever  built 
was  that  of  M.  G.  Trouve,  experimented  with  in 
Paris  in  1887.  This  motor  had  aluminum  circuits 
and  weighed  only  3.17  ounces,  but  developed  -g-V 
horsepower — at  the  rate  of  7.53  pounds  to  the 
horsepower,  a  figure  that  there  does  not  seem  to  be 
any  particular  prospect  of  reducing  in  any  prac- 
tical construction.  The  electric  motor  used  in  the 
Tissandier  dirigibles,  with  which  the  Tissandier 
brothers  experimented  in  France  in  1884  (see  Page 
81),  weighed  121  pounds  and  developed  a  maxi- 
mum of  only  1£  horsepower.  This  was  a  direct- 
current-motor.  Undoubtedly  alternating-current 
motors  can  be  built  considerably  lighter,  though  no 
serious  attempts,  founded  upon  the  present  state  of 
electrical  knowledge,  have  been  made  or  are  likely 
to  be  made  to  produce  them  for  aeronautical  uses. 

CUEEENT  SOUECES 

The  electric  motor,  unlike  the  gasoline  engine, 
is  not  a  prime  mover,  since  it  requires  a  supply 
of  electric  current  from  some  source  external  to 
itself  to  keep  it  going.  In  its  application  to  the 
propulsion  of  street-railway  cars  this  current  is 
developed  in  stationary  power  plants  and  trans- 
mitted to  the  moving  vehicles  by  sliding  or  roll- 
ing contacts  against  wires  or  other  conductors.  In 
electric  automobiles  current  is  supplied  by  storage 
batteries  carried  in  the  machine.  Obviously  the 
first  of  these  systems  is  not  applicable  in  any  prac- 
tical way  to  aerial  travel. 


306  VEHICLES  OF  THE  AIR 

Storage  Batteries,  or  accumulators,  do  not 
really  store  electric  current,  but  produce  it  by  chem- 
ical reactions,  exactly  as  is  the  case  with  pri- 
mary batteries.  They  differ  from  these,  however, 
in  that  the  chemical  elements  involved  in  their 
operation  can  be  electrolytically  recomposed  by  a 
passage  of  electric  current  through  the  cells  after 
each  period  of  discharge.  This  process  is  termed 
charging. 

The  best  modern  automobile  storage  batteries 
of  the  lead-plate  types  are  capable  of  delivering 
a  current  of  80  ampere  hours,  at  about  2  volts,  from 
each  five  pounds  of  weight.  Multiplying  the 
amperes  by  the  volts  and  dividing  the  watts  thus 
reached  by  746  (746  watts  being  the  electrical 
equivalent  of  a  horsepower)  it  is  found  that  about 
24  pounds  of  battery  are  required  to  maintain 
an  output  of  one  horsepower  for  one  hour,  against 
a  fuel  consumption  of  about  one-half  a  pound  per 
horsepower  hour  in  the  best  gasoline  engines. 

Much  effort  has  been  expended  in  attempts  to 
produce  storage  cells  much  lighter  for  a  given 
capacity  than  those  now  in  use,  and,  though  these 
cells  in  some  cases  give  better  results  than  the 
above  figures  indicate,  these  improved  results  in 
the  matter  of  capacity  per  unit  of  weight  usually 
are  attained  only  by  great  sacrifices  of  durability. 

By  many  engineers  the  most  promising  pos- 
sibility in  the  way  of  lighter  weight  storage  bat- 
teries is  considered  to  be  the  development  of  the 
so-called  alkaline  type  of  storage  cell,  of  which 
the  Edison  and  Jungmann  cells  are  today  the  prin- 


POWER  PLANTS  307 

cipal  exponents.  In  these  cells  the  elements  are 
metallic  nickel  and  iron,  and  nickel  and  cobalt 
oxide. 

Of  lead  storage  batteries,  there  are  two  prin- 
cipal types — the  formed  and  the  pasted.  In  the 
former  the  oxide  of  lead  that  constitutes  the  active 
material  is  formed  on  the  surfaces  of  the  electrode 
by  electro-chemical  processes  of  charging  and 
recharging,  while  in  the  latter  the  plates  are  cast 
lead  grids,  made  in  a  great  variety  of  forms,  and 
with  the  interstices  filled  with  oxide  of  lead  com- 
pressed in  place  under  high  pressure. 

Primary  Batteries,  though  not  totally  unavail- 
able as  a  source  of  current,  are  by  no  means  excep- 
tionally light  in  any  forms  now  known,  besides 
which  they  are  enormously  expensive  to  operate. 
The  plunge-bichromate  type,  in  which  the  electro- 
lyte is  bichromate  of  potash  in  which  are  immersed 
positive  and  negative  electrodes  of  zinc  and  carbon, 
respectively,  was  that  used  by  the  Tissandiers  (see 
Page  81),  the  total  weight  of  their  battery  being 
496  pounds.  While  it  is  perfectly  conceivable  that 
lighter  primary  batteries  may  be  produced  it  is  to 
be  regarded  as  certain  that  they  will  be  hopelessly 
expensive,  while  as  in  the  case  of  the  storage  bat- 
tery they  will  have  to  be  so  very  much  lighter 
before  they  can  find  any  considerable  utility  in 
application  to  aeronautics  that  the  prospect  of 
their  appearance  seems  very  remote. 

Thermopiles,  by  which  electricity  is  produced 
directly  from  heat,  are  today  interesting  devices 
of  the  physical  laboratory  rather  than  factors  in  the 


308  VEHICLES  OF  TEE  AIR 

world's  engineering  activities.  The  laws  of  ther- 
mopile action  are  only  imperfectly  understood,  but, 
in  a  general  way,  it  can  be  explained  that  the  typ- 
ical apparatus  of  this  kind  consists  of  assemblages 
of  numerous  dissimilar  metal  bars  or  parts,  joined 
together  by  their  ends  in  series.  When  the  points 
of  juncture  are  heated  the  result  is  that  an  electric 
current,  very  small  in  proportion  to  the  weight  of 
the  apparatus  and  the  quantity  of  heat  required, 
is  produced.  Moreover,  the  joints  tend  to  come 
apart  with  continued  use  and  it  is  found  rather 
difficult  to  localize  the  heat  as  it  should  be  for  the 
best  results.  The  metals  at  present  found  to  give 
the  most  efficient  results  are  bismuth  and  antimony 
in  combination.  It  is  a  recognized  remote  pos- 
sibility, however,  that  development  in  thermopiles 
may  some  day  revolutionize  present  methods  of 
power  development.  Possibly  the  road  to  such 
development  will  be  found  in  the  use  of  refractory 
metals  heretofore  little  tried  for  this  purpose,  such 
as  copper  and  iron,  or  metals  of  the  platinum 
group,  put  together  by  electric  or  autogenous  weld- 
ing, and  filamented  and  air-cooled  in  their  mid- 
dle portions  to  maintain  localization  of  the  heat. 

MISCELLANEOUS 

Besides  the  various  more-or-less  well-estab- 
lished or  well-investigated  power  sources  already 
considered,  there  are  a  few  more  freakish  and 
less  serious  possibilities  that  perhaps  call  for 
cursory  mention. 


POWER  PLANTS  309 

COMPEESSED  AIE 

Compressed  air,  or  liquid  air,  stored  under  high 
pressure  in  steel  cylinders,  has  been  used  with  some 
success  in  model  flying  machines — particularly  in 
those  of  Hargrave  (see  Page  122) — experimental 
automobiles,  mine  locomotives,  etc.,  the  power 
being  developed  from  it  through  practically  a 
type  of  small  steam  engine,  but  the  advantages  of 
this  system  are  most  manifest  in  almost  any  direc- 
tion but  that  of  light  weight,  so  its  application  to 
practical  aerial  navigation  is  not  likely. 

CAEBONIC  ACID 

Carbonic  acid  gas  can  be  used  in  much  the 
same  manner  as  compressed  air,  in  comparison  with 
which  it  has  minor  merits  and  still  more  serious 
shortcomings. 

VAPOE  MOTOES 

Vapor  motors — practically  small  steam  power 
plants  in  which  some  more  volatile  liquid  than 
water  is  used  to  produce  the  steam,  the  liquid 
being  recondensed  and  used  over  and  over — have 
long  offered  an  alluring  field  for  experiment, 
besides  which  they  found  rather  extensive  appli- 
cation to  motorboats  and  launches  before  the  days 
of  gasoline  engines. 

The  most  successful  type  of  vapor  motor  is  the 
common  naphtha  boat  engine.  Next  to  this  come 
various  types  working  with  acetone,  alcohol,  etc., 
few  of  which  have  run  outside  of  experimental 
workshops, '.and  all  of  which  are  heavy  and 
inefficient. 


310  VEHICLES  OF  THE  AIR 

SPEING  MOTOBS 

Spring  motors,  though  out  of  the  question  for 
the  propulsion  of  man-carrying  aerial  vehicles, 
have  served  and  continue  to  serve  a  considerable 
purpose  in  experimenting  with  models.  A  twisted 
rubber  band,  employed  as  suggested  at  a,  Figure 
29,  can  be  made  to  afford  a  surprising  amount  of 
energy  within  a  very  small  weight. 

Steel  springs  are  from  most  standpoints  less 
practical  than  rubber,  but  they,  too,  have  found  use 
in  models. 

A  bent  wood,  whalebone,  or  bamboo  splint,  or 
a  flat  steel  spring,  a,  furnishes  the  power  in  the 
well-known  form  of  toy  or  model  helicopter 
illustrated  in  Figure  28. 

ROCKET  SCHEMES 

Kocket  schemes,  in  which  propulsion  and  ascen- 
sion are  expected  to  be  secured  from  the  reaction 
of  sky-rocket-like  discharges  of  gas  from  explosion 
chambers,  have  been  a  recurring  feature  of  the 
theoretical  phase  of  aeronautical  development  for 
many  years.  All  such  schemes  seem  condemned  by 
the  fact  that  no  known  explosive  contains  anything 
like  as  many  heat  units  per  pound  as  a  great 
variety  of  true  fuels,  their  characteristic  feature 
being  not  a  capacity  for  great  power  output,  but 
simply  the  property  of  expending  their  entire 
energy  content  in  exceedingly  brief  spaces  of  time. 

TANKS 

The  tanks  for  transporting  the  fuel,  water,  and 
oil  necessary  to  the  operation  of  the  various  prac- 


POWER  PLANTS  311 

tical  types  of  aeronautical  power  plants,  must  ful- 
fill a  variety  of  conditions,  chief  among  which  are 
capacity,  strength,  light  weight,  immunity  from 
corrosion,  and — in  many  cases — a  form  favorable 
to  the  reduction  of  head  resistance.  For  any  given 
capacity  and  strength,  with  a  minimum  weight, 
spherical  tanks  are  best.  Immunity  from  corrosion 
is  generally  provided  by  the  use  of  copper  or  brass, 
but  steel  is  enough  stronger  to  warrant  its  use, 
protected  by  interior  and  exterior  plating  with 
other  metal.  The  form  most  favorable  to  progress 
through  the  air  with  a  minimum  resistance  is  the 
elongated  pear-like  form,  blunt-end  foremost,  next 
to  which  come  the  great  variety  of  elongated  cyl- 
inders and  other  possible  constructions  in  which 
circular  sections  are  a  feature.  Undue  elongation 
of  such  forms  adds  greatly  to  weight  and  so  reduces 
carrying  capacity  as  to  be  inexpedient  unless  in 
some  special  case  such  as  that  of  the  dirigible 
nacelle,  illustrated  in  Figures  19  and  20,  in  which 
the  tubular  tank  also  constitutes  a  stiffening  mem- 
ber in  the  framing. 

The  liquid  fuel  is  most  reliably  fed  to  the  motor 
by  gravity,  but  pressure  or  pump  feed  are  both 
employed,  and  can  be  made  very  satisfactory  with 
sound  designing,  as  has  been  well  established  in 
various  constructions  now  widely  recognized  as 
good  practice  in  automobile  engineering. 

A  point  of  particular  importance  when  large 
quantities  of  fuel  for  long  flights  are  carried,  is 
the  location  of  the  tank  at  the  center  of  gravity 
of  the  whole  machine,  so  its  gradual  emptying  will 


312  VEHICLES  OF  THE  AIR 

not  disturb  the  balance.  This  point  has  been  very 
carefully  observed  in  the  design  of  all  successful 
modern  aeroplanes,  including  the  Wright,  Bleriot, 
Antoinette,  and  other  machines.  The  same  point 
applies  with  equal  force  to  the  location  of  tanks  for 
water  and  oil,  and  the  seating  accommodations  for 
passengers. 


FIGURE  139. — Chain  Transmission  of  Wright  Biplane.     Note  the  crossing  of  tubular  chain- 
guides  at  the  left — also  the  placing  of  the  fuel  tank  t  at  the  center  of  gravity. 


140. — Double-Chain  Transmission  in   Hydroplane  Driven  by  Aerial  Propellers. 


CHAPTEE  SEVEN 

TRANSMISSION  ELEMENTS 

Except  in  the  case  of  a  flying  machine  in  which 
the  propeller  can  be  mounted  directly  upon  the 
engine  crankshaft,  it  is  necessary  to  have  some 
sort  of  a  transmission  to  communicate  the  power 
from  the  motor  to  the  propelling  element.  In  a 
number  of  the  most  successful  present-day  aero- 
planes the  designers  have  not  found  it  easy  to 
make  engine  location  and  engine  speed  readily 
coincident  with  propeller  location  and  propeller 
speed,  so  are  compelled  to  utilize  transmissions  of 
one  type  or  another  for  the  purposes  of  trans- 
mitting the  power  and  changing  the  relative  speeds 
of  rotation. 

Propeller-driving  arrangements  now  common 
in  aeroplane  practise  are  those  shown  in  Figures 


s 

FIGURE  133.  FIGURE  134.  FIGURE  135.  FIGURE  130. 

Comparison  of  Aeroplane  Transmission   Systems. 

133,  134,  and  136.  The  first  of  these  permits  the 
propeller  to  run  slower  than  the  engine,  as  in  the 
monoplanes  illustrated  in  Figures  141,  162,  and 

313 


314  VEHICLES  OF  THE  AIR 

198 ;  the  second  is  the  means  of  driving  the  oppo- 
sitely rotating  propellers  on  the  Wright  and  the 
Cody  biplanes,  as  is  more  clearly  shown  in  Figure 
188;  while  the  fourth  is  the  widely-favored  plan  of 
mounting  the  propeller  directly  on  the  engine  shaft, 
as  is  shown  in  many  of  the  illustrations  herein. 

A  transmission  is  imperatively  necessary  when 
more  than  one  propeller,  not  on  the  engine  shaft, 
is  run  from  a  single  motor  as  in  the  machines 
illustrated  in  Figures  20,  32,  33,  78,  79,  107,  134, 
140,  and  188. 

The  change-speed  gear,  so  necessary  in  auto- 
mobiles and  other  land  vehicles  to  allow  advan- 
tageous application  of  the  power  under  greatly 
varying  conditions  of  operation — up  and  down 
hills,  over  soft  and  hard  surfaces,  etc. — is  not 
required  in  flying-machine  transmissions  because 
the  conditions  under  which  aerial  vehicles  operate 
present  far  less  variation  in  so  far  as  the  matter  of 
power  demand  is  concerned. 

CHAINS  AND  SPEOCKETS 

Chains  and  sprockets,  of  proper  design,  are  one 
of  the  most  efficient  and  at  the  same  time  one  of 
the  lightest  and  most  flexible  of  all  known  means 
of  power  transmission,  as  is  evident  in  their  ex- 
ceedingly extensive  application  to  bicycles,  auto- 
mobiles, etc.  This  type  of  transmission  has,  more- 
over, given  good  results  in  several  of  the  most 
successful  aeroplanes  so  far  constructed. 

In  the  use  of  chains  it  is  essential  to  employ 
only  the  highest  quality  materials  and  the  most 


TRANSMISSION  ELEMENTS  315 

approved  designs.  Even  with  these  factors  closely 
looked  after  there  is  a  certain  amount  of  unavoid- 
able stretch  in  a  chain,  due  to  the  accumulated 
wear  at  each  link  and  rivet.  Lubrication,  too, 
must  be  provided  for,  preferably  by  occasionally 
soaking  in  a  mixture  of  graphite  and  melted  tal- 
low, or  by  dosing  liberally  from  time  to  time  with 
suitable  oils. 

Obviously,  the  difficulty  of  keeping  a  chain 
clean  and  properly  lubricated  is  much  less  on  a 
flying  machine  than  it  is  on  an  automobile  or 
bicycle,  it  being  much  less  exposed  to  dust. 

Chains  that  are  very  long  require  to  be  guided 
by  small  idlers  or  sleeves  of  some  sort.  An 
example  of  the  use  of  tubular  steel  sleeves  to  guide 
long  chains  is  afforded  in  the  transmission  of  the 
Wright  machine,  illustrated  in  Figure  188,  in 
which  it  is  seen  that  the  chain  for  the  propeller  a 
passes  through  the  two  slightly-diverging  tubes 
6  and  c,  while  that  for  the  propeller  d  goes  through 
the  tubes  e  f,  crossed  to  reverse  the  motion.  This 
very  peculiar  arrangement,  which  has  been  widely 
denounced  as  unmechanical,  has  for  its  object  the 
reversal  of  the  rotation  of  one  of  the  propellers 
so  that  the  two  may  turn  in  opposite  directions, 
as  is  required  to  balance  the  gyroscopic  and  other 
reactions.  That  it  has  serious  objections,  and  is 
justified  only  as  an  experimental  construction, 
has  been  suggested  in  several  cases  of  chain  break- 
age in  the  use  of  this  particular  type  of  machine. 

In  the  Cody  biplane  (see  Page  202)  chains  spe- 
cially made  for  this  purpose  by  an  English  manu- 


316  VEHICLES  OF  THE  AIR 

facturer  are  used,  their  special  feature  being  the 
provision  of  a  definite  amount  of  lateral  flexibility. 

Seemingly  a  better  plan,  certain  to  afford  about 
the  same  results,  would  be  to  provide  the  engine 
camshaft  with  heavier  driving  gears  and  a  heavy 
end  bearing,  so  that  one  of  the  propellers  could  be 
driven  from  a  sprocket  on  this  shaft,  the  cam  gear- 
ing reversing  the  motion  as  is  suggested  in  Figure 
135.  The  two-to-one  ratio  of  drive  secured  in  this 
way  could  be  readily  compensated  by  making  the 
right  propeller  sprocket  twice  as  large  as  the  left. 

Another  chain  transmission,  used  to  drive 
aerial  propellers  on  a  hydroplane  boat,  is  illus- 
trated in  Figure  140. 

With  proper  designing,  chains  can  be  satisfac- 
t^rily  run  at  speeds  as  high  as  2,000  feet  a  minute. 
Such  speeds  particularly  require  ample  clearance 
between  tooth  and  roller. 

BLOCK  CHAINS 

Block  chains,  of  the  type  pictured  in  Figure 
137,  are  distinguished  by  the  use  of  solid  steel 
blocks  for  each  alternate  link.  Block  chains  are 
much  used  on  bicycles  but  are 
objected  to  on  automobiles  be- 
is?.— Block  chain,  cause  they  run  very  hard  when 
not  clean — an  objection  that  is  not  a  very  serious 
one  from  the  flying-machine  standpoint.  Their 
advantages  are  their  greater  width  of  tooth  and 
rivet-bearing  surface  for  a  given  width  of  chain, 
their  simpler  construction  and  their  materially; 
lower  price. 


FIGURE  141. — Belt  Transmission  in  Recent  Santos  Dumont  Monoplane.  This  machine, 
while  it  was  not  conspicuously  successful,  is  a  notable  example  of  what  can  be  done  with 
belt  transmission,  the  light  weight  of  the  pulleys  6  &  and  the  ordinary  construction  of  the  belt 
a  a  being  particularly  interesting. 


TRANSMISSION  ELEMENTS 


317 


BOLLEE  CHAINS 

Roller  chains,  made  entirely  of  links,  rollers, 
and  rivets,  as  shown  in  Figure  138,  are  very  smooth 
running  even  when  very  dirty  and  are  capable  of 
running  smoothly  over  smaller 
sprockets  than  can  be  used  with 
block  chains.  The  greater  width  FIQURE  iss.— Roller  chain, 
of  roller  chains  for  given  bearing  widths  on  rivets 
and  sprocket  teeth  is  not  a  serious  objection  in 
most  cases,  since  it  involves  no  materially  greater 
weight. 

MISCELLANEOUS 

Silent  chains  and  link  belts  are  made  very  wide, 
of  great  numbers  of  metal  or  leather  links,  and  call 
for  special  sprockets  or  pulleys.  In  the  case  of 
some  link  belts  the  construction  is  such  that  a  small 
toothed  sprocket  can  be  used  at  one  end  and  a 
large  smooth  pulley  at  the  other,  the  belt  working 
satisfactorily  over  both. 

What  are  known  as  " cable  chains" — not  made 
to  run  over  sprockets — are  much  used  in  place  of 
sash  cords  and  the  like.  Their  strength  and  flexi- 
bility renders  them  ideal  for  use  in  control  connec- 
tions where  corners  must  be  turned. 

BLOCK  CHAINS 


Pitch 

Inside  Width 

Outside  Width 

Weight  to  Foot 

Breaking  Load 

inch 
inch 

i  *nc£ 

4  inch 

i   inch 

.073  pound 

300  pounds 

inch 

A  inch 

187  pound 

1500  pounds 

inch 

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318 


VEHICLES  OF  THE  AIR 


STANDARD  AMERICAN  ROLLER  CHAINS 


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ROLLER  CHAINS 


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2800  pounds 
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•  Bicycle  Chaiui. 


TRANSMISSION  ELEMENTS 


319 


CABLE  CHAINS 


Pitch 

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Depth 

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.267  inch 

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t  inch 

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t  These  can  be  run  as  block  chains  over  sprockets. 

BEVEBSIBLE  SPEOCKETS 

Sprockets  made  exactly  the  same  on  both  sides, 
so  that  it  does  not  matter  which  way  around  they 
are  fixed  in  place,  in  some  situations  constitute  a 
useful  provision  against  wear.  By  simply  turning 
such  a  reversible  sprocket  around  entirely  new 
wearing  surfaces  are  presented  to  the  chain.  This 
applies,  of  course,  only  to  transmissions  in  which 
all  or  most  of  the  work  is  done  in  one  direction  of 
rotation. 

For  best  results,  sprockets  with  not  more  than 
50  nor  less  than  14  teeth  are  advised  by  the  most 
conservative  chain  manufacturers. 

MISSED  TEETH 

In  the  design  of  very  large  sprockets  it  often  is 
a  useful  expedient  to  use  less  than  a  tooth  for  every 
link,  leaving  out  every  other  tooth,  for  example. 
This  reduces  friction,  slightly  lowers  weight, 


320  VEHICLES  OF  THE  AIR 

cheapens  construction,  and  is  quite  unobjection- 
able, except  that  it  is  not  applicable  to  small 
sprockets. 

SHAFTS  AND  GEARS 

Shafts  and  gears  for  the  transmission  of  power 
are  the  soundest  of  sound  engineering,  though  a 
given  amount  of  material  will  not  as  readily  sus- 
tain a  given  torsional  stress  in  a  shaft  as  it  will  a 
corresponding  tensile  stress  in  a  chain,  and  gears 
lack  the  flexibility  of  chain-and-sprocket  transmis- 
sion. Advantages  of  .shaft-and-gear  transmission 
are  its  ready  application  to  greater  distances  than 
can  be  effectively  worked  over  by  chains,  the  small 
space  it  occupies,  its  silence  and  smoothness  of 
running,  and  the  facility  with  which  it  can  be 
encased  and  lubricated. 

SHAFTS 

Hollow  rod  or  tubing,  of  the  finest  alloy  steels, 
of  circular  cross  section,  and  of  large  diameter  and 
with  comparatively  thin  walls,  is  much  the  highest 
grade  material — the  strongest  and  lightest — that 
can  be  used  for  shafting.  Solid  shafts  of  course 
have  their  uses,  as  for  passing  through  small  holes 
in  situations  where  more  room  cannot  very  readily 
be  provided,  but,  though  affording  the  greatest 
strength  that  can  be  had  in  a  given  space  they  do 
,not  begin  to  be  as  strong  for  a  given  weight  as 
hollow  material.  Always  when  it  is  possible 
unbroken  shaft  lengths  should  be  used  in  any 
machine  compelled  to  work  under  heavy  duty,  but 
there  are  reasons  preventing  this,  excellent 


TRANSMISSION  ELEMENTS  321 

joints  can  be  made  in  shaft  materials  by  brazing, 
or  by  autogenous  or  electric  welding.  In  Chapter 
11  further  data  is  given  concerning  stock  sizes  of 
shafting  and  tubing,  and  methods  of  assembling. 

SPUR  GEAES 

Spur  gears  for  the  transmission  of  power  are 
difficult  to  render  perfectly  smooth  running  be- 
cause of  the  slight  amount  of  backlash  that  results 
from  the  necessary  slight  clearance  given  between 
the  teeth  to  prevent  binding.  Consequently  they 
are  used  only  when  cost  has  to  be  considered,  or 
in  situations  in  which  peculiar  conditions  apply, 
such  as  the  necessity  for  endwise  meshing  of  the 
teeth  in  sliding  gears  for  automobiles.  Spur  gears 
can  transmit  power  only  between  parallel  shafts, 
and  it  is  most  essential  that  this  requisite  parallel- 
ism be  perfectly  secured  and  maintained  by  stiff 
construction  and  suitable  bearings.  Case-hard- 
ened steel  gears  are  the  only  kind  suitable  for 
heavy  power  transmission  with  light  weights. 
Theoretically  with  properly  cut  teeth  there  is  only 
rolling  contact  between  the  teeth  of  meshed  gears, 
but  practically  there  is  enough  sliding  friction  to 
warrant  the  provision  of  the  tough  shell  that  is 
produced  by  suitable  methods  of  case-hardening. 
With  such  case-hardening,  the  tough  interiors  of 
the  gear  teeth  resist  breakage,  while  their  hard- 
ened external  shells  withstand  wear. 

Spur-gear  drives  have  been  experimented  with 
in  one  or  two  of  the  Voisin  machines  (see  Chapter 


322  VEHICLES  OF  THE  AIR 

12),  with  a  view  to  running  the  single  propeller 
slower  than  the  engine. 

Bronze  or  brass  gears  meshed  with  steel,  or 
gears  built  up  laterally  of  rawhide  and  metal 
layers,  are  very  silent  running,  but  lack  the  req- 
uisite strength  and  durability  for  the  continued 
transmission  of  much  power  with  small  sizes. 
Gears  of  these  materials  are  much  used  for  cam- 
shaft, circulating-pump,  lubricator,  and  magneto 
driving. 

The  teeth  of  gears  are  cut  on  three  principal  sys- 
tems— the  involute,  the  epicycloid,  and  the  "stub." 
The  pitch  line  of  a  gear  is  the  working  diameter — 
about  the  height  of  a  tooth  less  than  the  actual 
diameter.  The  "pitch  line"  of  a  pair  of  meshed 
gears  can  be  seen  when  they  are  running,  appear- 
ing as  a  sort  of  shadow  line  about  midway  of  the 
tooth  lengths.  The  ' '  pitch ' '  of  gears  has  reference 
to  the  number  of  teeth  per  inch  of  diameter — "di- 
ametral pitch" — and  is  the  number  of  teeth  in 
3.1416  inches  of  the  pitch  line.  The  proper  pitch 
for  given  conditions  of  speed,  loading,  etc.,  as  well 
as  the  width  of  gears,  always  must  be  determined 
by  exhaustive  and  competent  consideration  of  the 
circumstances  of  the  particular  case. 

BEVEL  GEARS 

Just  as  spur  gears  are  suitable  for  the  trans- 
mission of  power  between  parallel  shafts,  bevel 
gears  are  designed  to  transmit  it  "around  corners" 
— between  shafts  at  angles  to  each  other.  Aside 
from  the  correct  tooth  outlines,  which  are  the  same 


TRANSMISSION  ELEMENTS  323 

for  bevel  gears  as  for  spur  gears,  the  essential 
thing  in  bevel-gear  design  is  that  all  lines  pro- 
longed from  the  tooth  surfaces  must  meet  at  the 
point  where  the  axes  of  rotation  of  the  gears  would 
meet  if  prolonged.  To  explain  this  more  simply, 
the  requirement  is  that  the  gears  be  adjacent  sec- 
tions of  two  toothed  cones,  of  the  same  or  different 
altitudes,  but  with  points  together  and  sides  in 
contact.  Miter  gears  are  bevel  gears  with  angles 
of  45°,  so  that  both  gears  of  a  pair  are  alike.  Such 
gears  are  used  at  a  a  and  6,  Figures  20  and  107, 
respectively. 

STAGGERED  AND  HERRINGBONE  TEETH 

By  placing  two  similar  spur  gears  side  by  side, 
with  the  teeth  of  one  opposite  the  space  between  the 
teeth  in  the  other,  and  meshing  the  staggered-tooth 
gear  thus  formed  with  another  of  similar  construc- 
tion, backlash  and  rough  operation  can  be  largely 
eliminated.  By  the  use  of  more  than  two  gears  in 
each  element  the  operation  can  be  still  further  im- 
proved until  with  an  infinity  of  steps  in  the  gear 
the  action  would  be  almost  perfect.  Such  an  in- 
finity of  steps  is  practically  secured  in  the  helical 
gear,  in  which  each  tooth  runs  at  a  slant  across  the 
gear  face.  An  objection  to  helical  gears  is  that 
the  slant  of  their  teeth  tends  to  force  them  out  of 
mesh  sidewise,  so  for  all  but  the  lightest  power 
transmission  the  double-helical,  the  so-called  "  her- 
ringbone" gear,  is  to  be  preferred.  In  this  type 
each  tooth  has  a  symmetrical  double  slant  from  a 
point  on  the  center  of  the  gear  face  to  its  edges,  so 


324  VEHICLES  OF  THE  AIR 

that  a  tendency  to  work  to  one  side  is  neutralized 
by  a  corresponding  tendency  to  work  to  the  other. 
The  helical  and  herringbone  systems  of  tooth  for- 
mation are  applicable  to  bevel  gears  as  well  as  to 
spur  gears,  though  in  the  first  case  they  are  much 
more  expensive  to  produce. 

BELTS  AND  PULLEYS 

For  the  transmission  of  large  amounts  of  power, 
belt-and-pulley  combinations  tend  to  work  out 
very  heavy  or  inefficient,  for  which  reason  they 
find  little  application  in  light-weight  power  plants 
except  for  driving  fans,  lubricators,  and  other  light 
accessory  devices.  An  exception  is  the  case  of  the 
motorcycle,  in  many  forms  of  which  belt  transmis- 
sion is  used  with  success.  The  great  advantage  of 
belt-and-pulley  transmission  is  its  extreme  flexibil- 
ity and  its  tendency  to  cushion  and  eliminate  slight 
irregularities  in  driving  by  its  tendency  to  slip 
under  sudden  increase  of  load. 

PULLEY  CONSTRUCTION 

Pulleys  are  variously  constructed  of  wood  and 
metal,  and  with  flat,  grooved,  and  crowned  faces. 
In  seeking  extreme  light  weight  with  a  requisite 
strength,  a  rim  of  wood  or  sheet  steel,  with  wire 
spokes  to  complete  it,  is  undoubtedly  the  ideal  con- 
struction. For  a  given  size,  grooved  pulleys,  by 
their  binding  action  upon  the  round  or  V-shaped 
belts  employed  with  them  transmit  the  most  power, 
but  also  lose  the  most  in  friction.  For  flat  belts 
wide  flat  pulleys  can  be  used  if  the  belt  is  perfectly 


TRANSMISSION  ELEMENTS  325 

uniform  and  the  pulleys  are  correctly  alined,  but  a 
preferable  construction  is  the  crowned  pulley,  with 
center  slightly  higher  than  the  edge,  so  that  it 
holds  the  belt  on  by  the  resistance  opposed  by  the 
edges  of  the  latter  to  stretching  over  the  high 
pulley  center. 

Metal  pulleys  often  are  faced  with  leather  or 
other  material,  cemented  on  to  increase  belt 
adhesion. 

Idlers  are  pulleys  arranged  to  press  against  belts 
running  over  other  pulleys  that  transmit  and  re- 
ceive the  power,  so  that  the  tension  and  consequent 
adhesion  can  be  adjusted  by  variation  of  the  idler 
pressure. 

BELT  MATERIALS 

Belts  are  mostly  made  of  leather,  rawhide,  can- 
vas, and  canvas  and  rubber,  and  may  be  flat,  round, 
or  V-shaped,  to  fit  corresponding  pulleys.  Some 
motorcycle  and  light  automobile  belts  are  made  of 
regular  link  chains  with  helical  leather  wrappings 
to  contact  with  the  pulleys.  The  advantage  of 
this  construction  is  the  elimination  of  stretch.  Belt 
dressings  usually  are  employed  to  secure  proper 
adhesion  to  the  pulleys  without  the  use  of  undue 
belt  tension,  which  causes  enormous  friction  losses. 

Interesting  applications  of  belt-and-pulley 
transmission  to  aeroplanes  are  shown  in  Figures 
Ml  and  217. 

CLUTCHES 

Up  to  the  present  time  there  has  been  little  use 
of  clutches  in  aeroplane  transmissions,  but  there  is 


326  VEHICLES  OF  THE  AIR 

no  doubt  but  what  some  such  disengaging  device 
will  become  increasingly  necessary  as  gliding  flight 
becomes  better  understood  and  therefore  more  fre- 
quently practised.  Present  propellers,  rather 
strongly  held  against  rotation  when  the  motor  is 
stopped,  must  present  much  more  resistance  to 
forward  movement  (besides  tending  to  tilt  the 
machine  when  only  one  is  used)  than  could  be  the 
case  if  they  were,  on  occasion,  allowed  to  spin  freely 
on  their  shafts. 

The  type  of  clutch  most  suitable  for  this  service 
is,  of  course,  an  undetermined  question.  The  vari- 
ous forms  of  friction  clutches — common  disk,  cone, 
contracting,  and  expanding  constructions  used  in 
automobile  practise— might  have  the  advantage 
that  at  the  end  of  a  period  of  gliding  they  would 
permit  utilization  of  the  propeller  as  a  sort  of 
windmill  wherewith  to  start  the  engine,  but  it  is 
more  probable  that  the  positiveness,  lightness,  and 
durability  of  simple  jaw  clutches  will  prove  to  be 
of  more  definite  merit. 


FIGURE   142. — Voisin   Biplane    Modified    into   a   Triplane. 


FIGURE  143. — Henry  Fai-man's  Biplane  in  Flight. 


CHAPTER  EIGHT 

BEARINGS 

From  nearly  every  vital  standpoint  a  most 
important  element  in  any  mechanism  are  the  bear- 
ings, since  it  is  upon  the  integrity  of  these  wear- 
ing surfaces  that  continued  serviceability  depends, 
besides  which  a  minimization  of  the  friction  losses 
in  bearings  directly  and  materially  affects  the 
amount  of  power  required  to  run  the  machine.  In 
aerial  vehicles  the  importance  of  durable  bearings, 
capable  of  long-continued  operation  without  atten- 
tion or  adjustment,  and  of  types  to  minimize  power 
lost  through  friction,  are  of  the  utmost  importance. 

In  the  history  of  mechanism  an  immense  vari- 
ety of  bearings  has  been  devised  to  serve  as  great 
a  variety  of  needs,  but  in  present-day  engineering 
sound  practise  has  settled  upon  a  few  long-tested 
forms  of  ball,  roller,  and  plain  bearings  as  most 
suitable  for  all  ordinary  purposes.  Each  of  the 
different  types  in  established  use  has  its  special 
merits,  and,  in  most  cases,  demerits,  so  a  choice  is 
usually  dictated  by  special  conditions  to  be  met.  It 
therefore  is  possible  to  generalize  only  to  the  extent 
of  emphasizing  the  importance  of  liberal  sizes  and 
best  materials,  as  sure  means  of  affording  strength, 
immunity  from  heating,  and  slow  wear. 

327 


328  VEHICLES  OF  THE  AIR 

BALL  BEARINGS 

Ball  bearings,  substituting  rolling  for  sliding 
contact  as  a  means  of  diminishing  friction,  are 
very  old  in  their  conception,  but  first  came  into 
general  practical  use  with  the  advent  of  the  bicycle. 
The  principle  upon  which  they  operate,  as  com- 
pared with  the  conditions  that  apply  in  a  plain 
bearing,  can  be  best  appreciated  from  considering 
the  analogous  cases  of  a  flat  board  laid  on  a  flat 
surface,  to  represent  the  plain  bearing,  and  the 
same  board  over  the  same  surface  but  with  a  num- 
ber of  marbles  beneath  it,  to  represent  the  ball 
bearing.  The  difference  in  friction  in  the  two 
cases  will  be  appreciated  by  any  one. 

Ball  bearings  manifest  their  superiority  in  the 
reduction  of  friction  loads  most  markedly  at  the 
moment  the  mechanism  is  started  in  motion,  the 
starting  effort  when  they  are  used  being  practically 
no  greater  than  the  effort  necessary  to  maintain 
the  mechanism  in  operation.  In  the  best  types 
of  plain  bearings,  in  which  running  friction  often 
is  reduced  to  a  very  small  degree,  the  friction  load 
at  starting  always  is  vastly  greater. 

The  best  types  of  modern  ball  bearings,  prop- 
erly applied,  can  be  counted  upon  to  reduce  friction 
losses  to  as  little  as  from  .0012  to  .0018  of  the  total 
load  per  bearing. 

ADJUSTABLE  BALL  BEAEINGS 

The  original  and  still  a  prevailing  type  of  ball 
bearing  is  the  so-called  "cup-and-cone",  or  adjust- 
able bearing,  in  which  the  inner  race  a,  Figure  144, 


BEARINGS  329 

takes  the  general  form  of  the  frustum  of  a  cone, 
while  the  outer  race  is  cup-like,  as  at  &,  the  ball 
circle  c  being  placed  between  the  two.  Bearings 
of  this  type  are  now  extensively  used  only  in 
bicycles  and  in  other  very  light  ma- 
chinery, or,  to  state  the  case  more 
strictly,  in  mechanisms  in  which  ex- 
cessive sizes  can  be  used  in  proportion 
to  the  loads. 

The  fundamental  theory  underly- 
ing the  construction  of  the  cup-and- 
cone  type  of  ball  bearing  is  that  of  its 

FIGURE  144.  J  * 

Adjustable  Baii  adjustability — a  theory,  however,  that 
is  found  to  fall  very  flat  upon  anal- 
ysis. Of  course,  it  is  evident  that  means  of  mov- 
ing the  cone  endwise  on  its  shaft,  or  the  cup  end- 
wise in  its  housing,  must  bring  the  two  closer 
together  or  farther  apart,  with  corresponding  vari- 
ation in  the  closeness  of  the  fit  upon  the  ball  circle. 
This  is  all  right  in  setting  up  a  new  bearing  but 
as  a  means  of  using  a  worn  bearing  its  merits  are 
less  apparent,  for  it  is  an  indisputable  fact  that 
such  wear  as  takes  place  must  take  the  form  of 
grooves  worn  in  the  races,  which  being  admitted, 
the  conclusion  is  inevitable  that  this  groove  is  cer- 
tain to  be  deeper  on  the  loaded  side  of  the  non- 
rotating  race.  This  being  the  case,  any  attempt 
at  adjustment  simply  results  in  the  appearance  of 
tight  and  loose  positions — alternate  binding  and 
rattling — as  the  bearing  is  turned,  causing  rough 
operation  and  rapid  breakdown,  and  thoroughly 
upholding  the  contention  of  the  advocates  of  annu- 


330 


VEHICLES  OF  THE  AIR 


lar  bearings  to  the  effect  that  any  ball  bearing  worn 
enough  to  require  adjustment  is  worn  enough  to 
throw  away. 

Most  high-grade  adjustable  ball  bearings  are 
made  with  " retainers"  to  hold  the  balls  assembled 
in  the  circle.  Such  retainers  usually  are  of  thin 
sheet  metal,  lightly  embracing  the  balls  so  that  they 
cannot  fall  apart  when  handled,  but  of  such  shape 
that  they  do  not  come  into  contact  with  the  races 
when  the  bearing  is  assembled. 

ANNULAB  BALL  BEAEINGS 

"Annular  ball  bearings,  of  the  type  illustrated 
in  Figure  145,  are  a  decidedly  modern  and 
advanced  development  in  engineering,  only  recently 
commencing  to  find  extensive  application  in  auto- 
mobiles and 
in  a  few  oth- 
er special  ex- 
amples of  ex- 
ceedingly 
high-  grade 
machinery. 

In  the  evolution  of  annular-ball  bearings  the 
ideal  held  in  view  has  been  to  substitute  in  place 
of  adjustment  a  decreasing  necessity  for  adjust- 
ment, by  providing  ball  and  race  surfaces  of  the 
hardest  and  strongest  materials  and  the  utmost 
accuracies  of  fit.  How  completely  this  ideal  is 
embodied  in  some  of  the  best  modern  annular  bear- 
ings will  be  appreciated  from  the  fact  that  these 
bearings,  used  in  sizes  properly  proportioned  to 


FIGURE  145. — Annular  Ball   Bearing.     Plan,   Sec- 
tional, and  Perspective  Views. 


BEARINGS  331 

the  work  to  be  done,  protected  from  grit  and  rust, 
and  properly  lubricated,  may  be  relied  upon  to 
outlast  almost  any  other  part  of  any  mechanism  in 
which  they  can  be  placed. 

All  successful  annular  bearings  consist  essen- 
tially of  the  inner  race  a  and  the  outer  race  b, 
Figure  145,  both  ring-like,  and  symmetrical  or 
approximately  symmetrical  in  their  sectional 
aspect,  with  the  ball  circle  between  them,  the  balls 
running  in  grooves  of  circular  cross  section,  the 
arcs  of  these  cross  sections  being  of  slightly  greater 
radii  than  the  radii  of  the  balls  themselves.  This 
results  in  two-point  contact,  with  the  two  points  in 
the  same  rotational  plane  and  on  opposite  sides  of 
the  balls. 

Many  different  schemes  have  been  devised  for 
assembling  annular  ball  bearings  in  a  permanent 
and  satisfactory  manner,  it  being  obvious  that  a 
full  circle  of  balls  cannot  be  placed  in  races  of  the 
type  shown  at  a  and  b,  Figure  145,  without  some 
special  scheme.  One  of  the  best  expedients  is  that 
shown  in  this  Figure,  in  which  only  a  half -circle  of 
balls  is  placed  in  the  bearing,  these  balls  being 
subsequently  spaced  out  to  fill  the  entire  circle  by 
the  interposition  of  the  small  spacing  springs 
shown  at  d. 

Another  construction  is  that  sketched  in  Fig- 
ure 146,  in  which  openings  e  and  /  are  made  in 
the  sides  of  the  races,  the  balls  being  forced  through 
these,  one  at  a  time,  by  the  application  of  slight 
pressure.  It  is  obvious  that  this  scheme  weakens 
the  races  to  some  extent,  besides  which  in  some 


332 


VEHICLES  OF  THE  AIR 


jit 

FlGUBB      146. — F  U  1 1 

Type  Annular  Ball 
Bearing.  The  balls  are 
introduced  through  the 
cross  slots,  e  and  f. 


forms  it  has  been  found  to  permit  escape  of  the 
balls  under  certain  conditions,  though  this  is  ren- 
dered less  likely  to  occur  by  the 
expedient  of  crossing  the  two 
openings,  e  and  f,  so  so  that  a 
slight  relative  rotation  between 
the  two  races  is  required  for  the 
insertion  or  removal  of  each  ball. 
Another  scheme  that  utilizes 
a  half -circle  of  balls,  thus  avoid- 
ing cutting  the  races,  is  to  use  spreading  retainers 
of  the  type  shown  in  Figure  147,  instead  of  the 
spring  separators  shown  in  Figure 
145. 

A  non-adjustable  ball  bearing 
with  flat  instead  of  grooved  outer  ball 
track  is  shown  in  section  in  Figure 
148,  in  which  it  is  seen  that  assem- 
bling with  a  full  circle  of  balls  is  ef- 
fected simply  by  placing  the  races  to- 
gether sidewise.  Flat  surfaces  will 
not,  however,  carry  as  heavy  loads  with  given  sizes 
as  can  be  carried  in  grooved  races. 

Annular  ball  bearings  of 
the  type  illustrated  in  Figure 
145  are  capable  of  perfectly 
satisfactory  operation  at  most 
enormous  rotational  speeds  — 
up  to  10,000  and  12,000  revolu- 
tions a  minute — will  stand  such 
shocks  as  are  imposed  on  gas- 
engine  crankshafts,  and  are  commonly  used  in  a 


FIGURE  147. — 
A  n  n  u  1  ar  Ball 
Bearing.  A  sheet 
metal  cage  is  em- 
ployed to  main- 
tain the  spacing 
of  the  balls. 


FIGUBB     148. — Annular 
Ball  Bearing. 


BEARINGS  333 

great  range  of  sizes,  from  bearings  less  than  one 
inch  in  diameter  up  to  the  sizes  required  for  heavy 
hoisting  cranes,  railway-car  axles,  turbines,  etc. 

It  is  rather  a  remarkable  fact 
that  annular  ball  bearings  of  the 
type  illustrated  in  Figure  145  prove 
remarkably  well  adapted  to  sustain 
thrust  as  well  as  the  radial  loads  to 
which  they  would  seem  more  par- 
ticularly adapted.  The  reason  for 
this  seems  to  be  disclosed  in  some 

Subjected  to  Thrust.  ,  , . . .  .  ,     ,     . 

such  condition  as  is  suggested  in 
Figure  149,  in  which  it  is  seen  that  crowding  the 
races  a  and  &  in  the  contrary  directions  indicated 
by  the  arrows  has  the  effect  of  rolling  the  balls 
slightly  upon  the  side  surfaces  of  the  respective 
race  grooves,  thus  causing  them  to  receive  fairly 
direct  side  support  against  the  load,  instead  of  the 
wedging  that  would  be  assumed  from  a  more  casual 
consideration. 

It  is  considered  by  the  best  authorities,  how- 
ever, that  combined  thrust  and  radial  loading  of  the 
same  bearing  is  always  objectionable  unless  the 
sum  total  of  the  loads  is  materially  less  than  the 
rated  capacity  of  the  size  of  bearing  used.  For  this 
reason  it  is  regarded  as  best  practise  in  such  condi- 
tions to  use  two  bearings  placed  closely  together, 
one  provided  with  an  endwise-sliding  fit  in  its  hous- 
ing so  that  it  can  carry  radial  load  only,  and  the 
other  made  radially  free  so  that  it  can  carry  thrust 
load  only. 

Special  types  of  ball  thrust  bearings  are  made 


334  VEHICLES  OF  THE  AIR 

in  the  form  illustrated  in  Figure  150,  in  which  the 
load  is  applied  through  the  flat  race  a,  through  the 
ball  circle,  and  to  the  race  ~b,  which  is  either  ground 
with  a  spherical  surface,  or  placed  in  a  spherically- 
seated  holder,  so  that  adjustment  will  occur  auto- 
matically to  slight  discrepancies 
of  alignment  due  either  to  im- 
perfect fitting  or  to  movement 
while  running.  Thrust  bearings 
of  these  types,  though  capable 
FIGURE  150.  —  Bail  of  carrying  very  heavy  loads, 

Thrust  Bearing.    The  flat  *  J  J 

cannot  be  run  at  as  high  speeds 


Jphlric'ailSref^mi*    as  the  radial  bearings  illustrated 

ting  it  to  adjust  itself  by       .         -r-,.  -t  AC\         i  i      i' 

movement  as  suggested    in  Figure  142  when  used  ior 

by  the  dotted  lines. 

thrust. 

All  the  annular  bearings  so  far  shown  consti- 
tute permanently  assembled  units,  requiring  no 
retainers  to  keep  them  together.  Thrust  bearings, 
however,  of  the  type  illustrated  in  Figure  150, 
often  are  made  with  retainers  to  hold  the  ball 
circles  together  for  convenience  in  handling. 

In  applying  annular  ball  bearings  it  is  nec- 
essary to  turn  in  the  housings  and  on  the  shafts 
simply  plain  cylindrical  seats,  that  for  one  race 
being  a  light  driving  fit  while  that  for  the  other 
is  a  close  sliding  fit.  Usually  the  inner  race  is 
given  the  driving  fit. 

A  frequent  misconception  with  reference  to  ball 
bearings  is  that  which  regards  them  as  having  a 
tendency  to  force  apart  the  balls  under  load,  as 
would  be  the  case  at  A,  Figure  151,  were  the  shaft 
a  to  bear  as  indicated  by  the  large  arrow  on  the 


BEARINGS  335 

two  balls  &  and  c,  resting  on  the  plane  surface,  in 
which  case  the  balls  would  tend  to  separate  as  indi- 
cated by  the  small  arrows.  The 
actual  condition  in  the  ball 
bearing,  however,  is  that 
sketched  at  B,  Figure  151,  in 
FIGURE  i5i.— Ruitants  which  the  curved  surface  e  is 
3earing'  substituted  for  the  plane  sur- 
face so  that  the  load  represented  by  the  large  arrow 
is  squarely  met  by  the  tangents  /  and  g,  normal  to 
which  come  the  two  resultant  thrusts  indicated  by 
the  small  arrows.  This  point  once  grasped  it  will 
be  readily  appreciated  how  erroneous  are  notions 
to  the  effect  that  ball  bearings  of  the  full  type  oper- 
ate with  pressure  between  adjacent  balls  (which  of 
course  revolve  in  opposite  directions,  as  shown  at  g 
and  h,  Figure  146)  or  that  the  balls  exert  pressure 
on  spacer  springs  or  retainers  used  to  hold  them 
apart  as  in  Figures  145  and  147.  Were  the  condi- 
tion illustrated  at  A,  Figure  151,  to  hold  true,  ball 
bearings  always  would  operate  with  the  lost  motion 
between  the  balls  represented  by  a  separation  at  the 
bottom,  instead  of  at  the  top  as  is  actually  proved 
the  case  by  the  click  which  every  one  has  noticed  in 
bicycle  ball  bearings,  and  which  is  due  to  the  balls 
falling  one  after  another  over  the  highest  point  in 
the  circle  of  rotation. 

It  is  a  common  idea  that  ball  bearings  do  not 
require  to  be  lubricated.  This  is  absolutely  wrong, 
and  serious  injury  can  be  quickly  done  to  a  ball 
bearing  by  any  failure  to  lubricate  properly.  It  is 
a  fact  though  that  very  infrequent  and  slight  lubri- 


336  VEHICLES  OF  THE  AIR 

cation  is  sufficient  for  most  ball  bearings,  provided 
they  are  properly  housed. 

As  has  been  previously  suggested,  it  is  of  the 
utmost  importance  that  ball  bearings  be  protected 
from  the  entry  of  grit,  and  from  such  rusting  as  is 
sure  to  follow  the  entry  of  water  or  the  existence 
of  acid  in  the  lubricant  used. 

Ball  bearings  depend  absolutely  for  durability 
and  efficiency  on  the  almost  perfect  wearing  sur- 
faces that  are  provided,  it  being  well  established 
that  minute  inequalities  in  these  surfaces  do  not 
wear  smooth  but  tend  to  break  down  into  greater 
inequalities,  from  all  of  which  it  can  be  readily 
inferred  that  quick  deterioration  is  the  logical 
sequence  of  dirt  or  rust.  Even  graphite  used  as  a 
lubricant  is  detrimental  in  good  ball  bearings,  in 
which  the  fits  are  so  close  as  not  to  provide  suffi- 
cient clearances  for  the  exceedingly  small  particles 
of  graphite  to  pass  between  adjacent  surfaces. 

Most  manufacturers  of  ball  bearings  specify  the 
types  of  mountings  they  consider  most  suitable  for 
housing  and  protecting  their  particular  product — 
for  keeping  out  water  and  grit,  and  retaining  the 
lubricant.  It  generally  pays,  in  the  designing  of 
most  mechanisms,  to  pay  close  regard  to  such  sug- 
gestions. 

The  following  tables  show  sizes,  rated  load 
capacities,  and  weights  of  one  of  the  oldest  makes 
of  modern  ball  bearings,  to  which  most  other  makes 
conform  exactly  in  the  use  of  the  same  metric 
sizes,  and  more  or  less  closely  in  qualities  of  design 
and  material: 


ANNULAR  BALL-BEARING  SIZES,  CAPACITIES.  AND  WEIGHTS 


LIGHT-WEIGHT  SERIES 

BORE 

DIAMETER 

WIDTH 

T  f\n  A     * 

Tirr_  •  _i_  4. 

Milli- 

Approxi- 
mate 

Milli- 

Approxi- 
mate 

Milli- 

Approxi- 
mate 

MMM 
in 

vv  eigu  i 
in 

meters 

equivalent 
in  inches 

meters 

equivalent 
in  inches 

meters 

equivalent 
in  inches 

pounds 

pounds 

10 

0.3937 

80 

.1811 

9 

0.3543 

120 

0.09 

12 

0.4724 

32 

.2598 

10 

0.3937 

140 

0.10 

15 

0.5905 

35 

.3779 

11 

0.4831 

160 

0.12 

17 

0.6693 

40 

.5748 

12 

0.4724 

250 

0.18 

20 

0.7874 

47 

.8503 

14 

0.5512 

320 

0.23 

25 

0.9842 

52 

.0473 

15 

0.5905 

850 

0.26 

30 

.1811 

62 

.4410 

16 

0.6299 

550 

0.44 

35 

.3779 

72 

.8346 

17 

0.6693 

600 

0.66 

40 

.5748 

80 

.1496 

18 

0.7086 

860 

0.83 

45 

.7716 

85 

.3464 

19 

0.7480 

950 

0.96 

50 

.9685 

90 

.5433 

20 

0.7874 

1000 

1.09 

55 

2.1653 

100 

.9370 

21 

6.8268 

1160 

1.36 

60 

2.3622 

110 

.3307 

22 

0.8661 

1550 

1.75 

65 

2.5590 

120 

.7244 

23 

0.9055 

1670 

2.28 

70 

2.7559 

125 

4.9212 

24 

0.9449 

1820 

2.50 

75 

2.9527 

130 

5.1181 

25 

0.9842 

2130 

2.63 

80 

3.1496 

140 

5.5118 

26 

1.0236 

2650 

8.22 

85 

3.3464 

150 

5.9055 

28 

1.1028 

2850 

8.97 

90 

3.5433 

160 

6.2992 

80 

1.1811 

8400 

4.84 

95 

3.7402 

170 

6.6929 

82 

1.2598 

3750 

5.94 

100 

3.9370 

180 

7.0866 

34 

1.3386 

2950 

7.17 

105 

4.1338 

190 

7.4803 

86 

1.4173 

4600 

8.48 

110 

4.3307 

200 

7.8740 

88 

1.4960 

5000 

10.26 

MEDIUM-WEIGHT  SERIES 

10 

0.3937 

85 

1.3779 

11 

0.4331 

200 

0.11 

12 

0.4724 

37 

1.4567 

12 

.4724 

240 

0.14 

15 

0.5905 

42 

1.6535 

13 

.5118 

280 

0.19 

17 

0.6693 

47 

1.8503 

14 

.5512 

870 

0.25 

20 

0.7874 

52 

2.0473 

15 

.5905 

440 

0.33 

25 

0.9842 

62 

2.4410 

17 

.6698 

620 

0.53 

30 

1.1811 

72 

2.8846 

19 

.7480 

860 

0.77 

35 

1.3779 

80 

3.1496 

21 

.8268 

1100 

0.98 

40 

1.5748 

90 

3.5433 

23 

.9055 

1450 

1.35 

45 

1.7716 

100 

3.9370 

25 

.9842 

1750 

1.79 

50 

1.9685 

110 

4.3307 

27 

.0630 

2100 

2.35 

55 

2.1653 

120 

4.7244 

29 

.1417 

2400 

2.99 

60 

2.3622 

130 

5.1181 

31 

.2205 

2800 

3.72 

65 

2.5590 

140 

5.5118 

33 

.2992 

3300 

4.49 

70 

2.7559 

150 

5.9055 

85 

.3779 

4000 

5.46 

75 

2.9527 

160 

6.2992 

37 

.4567 

4400 

6.58 

80 

3.1496 

170 

6.6929 

39 

.5354 

5000 

7.89 

85 

3.3464 

180 

7.0866 

41 

.6142 

5700 

9.27 

90 
95 

3.5433 

3.7402 

190 
200 

7.4803 
7.8740 

43 
45 

.6929 
.7716 

6400 
7000 

10.47 
12.27 

100 

3.9370 

215 

8.4645 

47 

.8504 

7700 

15.23 

105 

4.1338 

225 

8.8582 

49 

.9291 

8400 

1719. 

110 

4.3307 

240 

9.4488 

50 

.9685 

10000 

2029. 

*  Under  uniform  load  ;  from 


to  %  less  under  shock. 
337 


338 


VEHICLES  OF  THE  AIR 


HEAVY-WEIGHT  SERIES 


B 

ORE 

DIA] 

ftETER 

VI 

DTH 

Milli- 

Approxi- 
mate 

Milli- 

Approxi- 
mate 

Milli- 

Approxi- 
mate 

Load  * 
in 

Weight 
in 

meters 

equivalent 
in  inches 

meters 

equivalent 
in  inches 

meters 

equivalent 
in  inches 

pounds 

pounds 

17 

0.6693 

62 

2.4410 

17 

0.6693 

850 

0.56 

20 

0.7874 

72 

2.8346 

19 

0.7480 

1050 

0.85 

25 

0.9842 

80 

3.1496 

21 

0.8268 

1320 

1.14 

30 

.1811 

90 

3.5433 

23 

0.9055 

1600 

1.56 

35 

.3779 

100 

3.9370 

25 

0.9842 

1900 

2.00 

40 

.5748 

110 

4.3307 

27 

1  .0630 

2200 

2.58 

45 

.7718 

120 

4.7244 

29 

.1417 

2500 

3.33 

50 

.9685 

130 

5.1181 

31 

.2205 

3400 

4.18 

55 

2.1653 

140 

5.5118 

33 

.2992 

3900 

5.07 

60 

2.3622 

150 

5.9055 

35 

.3779 

4400 

6.12 

65 

2.5590 

160 

6.2992 

87 

.4567 

4900 

7.22 

70 

2.7559 

180 

7.0866 

42 

1.6535 

6200 

10.54 

80 

3.1496 

200 

7.S740 

48 

1.8897 

7300 

14.58 

00 

3.5433 

225 

8.8582 

54 

2.1260 

10000 

20.15 

100 

3.9370 

265 

10.4330 

60 

2.3622 

14000 

33.44 

*  Under  uniform  load ;  from  ya  to  %  less  under  shock. 

By  most  manufacturers  of  ball  bearings  it  is 
considered  bad  practise  to  attempt  to  divide  a  given 
load  among  several  closely-spaced  bearings,  such 
attempts  being  almost  always  attended  by  difficul- 
ties unless  special  provision  is  made  to  prevent 
unequal  distribution  of  the  load  on  the  two  bear- 
ings, causing  one  to  support  greater  loads  than  are 
calculated  for  it,  with  undue  wear  as  a  result. 
Nevertheless,  annular  ball  bearings  are  now  built 
with  double  grooves  in  single  races,  with  the  idea 
of  sustaining  a  given  load  in  a  smaller  circumfer- 
ential space.  Bearings  of  this  type  are  so  new 
that  their  success  is  fairly  to  be  considered  more 
or  less  problematical,  though  in  many  initial  appli- 
cations they  appear  to  give  excellent  service.  Obvi- 
ously, nothing  but  the  most  superior  accuracy  can 
be  considered  permissible  in  a  construction  of  this 
sort. 


BEARINGS  339 

All  ball  bearings  of  any  quality  are  constructed 
of  the  highest  grades  of  alloy-steels  made  glass- 
hard  throughout,  or  at  least  of  high-grade  carbon 
steels,  casehardened.  Both  races  and  balls  should 
be  finished  to  mirror  surfaces,  to  within  ^Vir  or 
TTFTOTF  of  an  inch  of  true  size,  and  the  balls  must  be 
closely  tested  and  selected  for  size  and  sphericity. 

ROLLER  BEARINGS 

Roller  bearings  are  analogous  to  ball  bearings 
in  that  they  substitute  rolling  for  sliding  friction, 
but  instead  of  employing  a  point  of  contact  on  the 
surface  of  a  sphere  as  in  the  ball  bearing,  a  line 
contact  is  employed  along  the  side  of  the  cylinder 
or  conical  roller,  the  analogy  given  on  Page  328 
fitting  this  case  if  for  the  marbles  there  be 
substituted  small  rollers. 

The  difficulty  of  making  rollers  and  races  close 
enough  to  the  theoretically  true  surfaces  required 
is  the  one  serious  difficulty  in  the  manufacture  of 
roller  bearings,  since  if  anything  materially  short 
of  the  utmost  possible  perfection  be  tolerated  the 
result  is  certain  to  be  unequal  wear,  if  not  absolute 
breakage,  of  the  rollers.  Also,  the  idea  that  a  roller 
bearing  is  capable  of  carrying  greater  loads  than  a 
ball  bearing  of  approximately  the  same  size — qual- 
ity of  materials  and  workmanship  being  equal — is 
probably  erroneous,  it  being  founded  upon  the 
incorrect  theory  that  rollers  afford  greater  areas 
of  contact  than  balls.  It  is  evident  that,  contact 
with  the  ball  being  an  infinitely  small  point  and 
that  with  the  roller  an  infinitely  narrow  line,  the 


340  VEHICLES  OF  THE  AIR 

area  in  one  case  is  theoretically  no  greater  than  the 
other,  being  zero  in  both  cases.  Practically,  how- 
ever, definite  bearing  area  is  secured  in  both  types 
of  bearings  by  the  slight  deformation  of  the  bear- 
ing surfaces  which  cannot  fail  to  result,  even  with 
the  most  resistant  materials,  under  load.  In  the 
case  of  ball  bearings  under  this  deformation  the 
point  becomes  a  circle,  while  in  the  roller  bearing 
the  line  becomes  a  rectangle  and,  with  loads  and 
materials  similar  in  both  cases,  the  deformations 
are  found  to  be  approximately  so  proportioned 
that  the  area  of  the  circle  in  one  case  is  practically 
as  great  as  the  area  of  the  rectangle  in  the  other, 
thus  giving  the  ball  bearing  as  great  wearing  sur- 
face as  is  secured  in  the  roller  bearing — not  to 
consider  the  obvious  advantages  in  ease  of  manu- 
facture and  perfection  of  operation  in  favor  of 
the  ball. 

CYLINDBICAL  ROLLER  BEARINGS 

Cylindrical  roller  bearings  usu- 
ally are  assembled  in  plain,  cylin- 
drical, ring-like  races,  as  shown  in 
Figure  152.  Making  the  rollers  very 
short  tends  to  minimize  any  lateral 
inequalities  of  loading  due  to  devia- 

FlGDRE    152.—  °_      .         -      - 

cylindrical  Roi-   tions  f rom  truly  cylindrical  form. 

ler  Bearing. 

FLEXIBLE  ROLLER  BEARINGS 

Flexible  roller  bearings,  of  the  description 
illustrated  in  Figure  153,  are  a  type  possessing 
many  excellent  qualities,  and  therefore  widely  used 


BEARINGS  341 

in  cheaper  automobiles  and  other  classes  of  machin- 
ery. In  these  bearings,  instead  of  attempting  to 

secure  exceedingly  accu- 
rate fits,  the  necessity 
for  exceedingly  accurate 
fitting  is  avoided  by  the 
scheme  of  making  the 

FIGURE   153. — Flexible  Roller  ,_  /»        .       ••         •    • 

Bearing.  rollers   of   steel   strips, 

flexible  enough  to  adjust  themselves  to  minor  ine- 
qualities of  shaft  and  housing.  The  rollers  being 
hollow,  as  at  a,  with  a  helical  opening  between  adja- 
cent turns  of  the  strips,  the  oil  distribution  is  excel- 
lently provided  for.  The  housing  6  is  used  as  a 
liner  for  the  space  within  which  the  bearing  is 
placed. 

TAPEEED  EOLLEB  BEAEINGS 

Tapered  roller  bearings,  employing  rollers 
made  in  the  form  of  the  frustum  of  a  cone,  have 
the  advantage  over  other  types  of  roller  bearings 
that  they  are  adjustable  for  wear  by  lateral  move- 
ment of  the  races,  but  in  this  case  the  same  objec- 
tion holds  that  holds  against  adjustable  ball  bear- 
ings— that  the  loaded  side  of  the  non-rotating  race 
wears  faster  than  any  other  part  of  the  bearing 
and  this  causes  a  flattening  of  one  side  of  the  proper 
circle  of  travel.  In  well  designed  roller  bearings 
of  good  material  this  flattening  does  not  occur  at 
a  very  rapid  rate,  so  it  is  not  necessarily  inconsist- 
ent with  long  life,  but  it  does  make  practically  use- 
less the  provision  for  adjustment  except  as  this  is 
found  advantageous  in  the  original  assembling. 

Roller  bearings,  like  ball  bearings,  must  be 


342  VEHICLES  OF  THE  AIR 

made  of  high-grade  steel — preferably  alloy  steel, 
though  carbon  steels  often  are  made  to  serve  the 
purpose. 

PLAIN  BEARINGS 

Plain  bearings  are  the  earliest  of  all  types  and 
in  their  best  forms  still  possess  important  appli- 
cations, their  greatest  advantage  aside  from  their 
cheapness  being  the  requirement  of  smaller  cir- 
cumferential (though  greater  lateral)  space  for  a 
given  load  than  is  necessary  with  ball  or  roller 
bearings. 

When  made  of  suitable  materials,  finished  to 
insure  distribution  of  the  load  over  the  entire  bear- 
ing surfaces  and  provided  with  sufficient  and 
unfailing  lubrication,  plain  bearings  are  service- 
able and  long-lived,  and  capable  of  operation  with- 
out undue  friction  loss. 

PLAIN  BEARING  MATERIALS 

A  wide  range  of  different  metals  is  suitable  for 
plain  bearings,  one  surface  of  which  usually  is  that 
of  the  shaft  itself.  In  most  plain-bearing  mechan- 
isms the  combination  is  a  steel  shaft  running  in 
contact  with  some  other  metal. 

Steel  as  a  material  for  plain-bearing  surfaces 
is  much  better  than  is  commonly  supposed.  There 
is  in  fact  little  in  the  whole  range  of  engineering 
experience  or  knowledge  to  condemn  the  use  of 
steel  against  steel,  though  it  is  essential  that  this 
combination  of  bearing  surfaces  be  exceptionally 
well  finished  and  perfectly  lubricated  if  heating, 


BEARINGS  343 

with  consequent  wear  and  " seizing",  are  to  be 
avoided.  Steel-to-steel  permits  higher  loads  to  a 
given  area  than  can  be  safely  carried  on  any  other 
materials. 

Cast  Iron  as  a  material  for  bearing  boxes  is  like 
steel  a  material  of  superior  qualities,  though  it  is 
little  used  for  this  purpose.  It  is,  indeed,  subject 
only  to  the  twin  disabilities  of  requiring  excep- 
tionally accurate  finish  and  thoroughly  adequate 
lubrication. 

Bronzes,  of  copper  and  tin,  and  especially  those 
alloys  in  which  the  tin  component  rises  very  high, 
with  possibly  some  admixture  of  antimony,  lead, 
or  other  fusible  metals,  are  widely  favored  as  a 
material  for  plain  bearings. 

Brasses,  through  a  wide  range  of  common 
alloys,  possess  many  of  the  same  bearing  qualities 
as  the  bronzes. 

Babbitt,  an  alloy  of  tin,  lead,  and  antimony,  in 
proportions  that  vary  somewhat  with  the  ideas  of 
different  manufacturers,  is  perhaps  the  most  ex- 
tensively-used and  generally-serviceable  plain- 
bearing  material  known.  In  its  best  qualities  it 
reduces  sliding  friction  almost  to  its  lowest  terms, 
besides  which  it  possesses  the  advantage,  not  pos- 
sessed by  brasses  and  bronzes,  of  melting  out  if 
the  bearing  overheats  through  inadequate  lubrica- 
tion, thus  avoiding  the  injury  to  the  shaft  which 
is  certain  to  ensue  when  a  brass  or  bronze  bearing 
seizes.  Babbitt  requires,  however,  larger  areas  for 
given  loads  than  are  found  sufficient  for  plain 
bearings  of  harder  metals. 


344  VEHICLES  OF  THE  AIR 

Graphite,  in  the  form  of  compressed  bushings 
surrounding  a  shaft,  is  under  reasonable  loads 
much  more  durable  than  would  be  imagined,  and 
has  the  advantage  of  operating  without  lubrica- 
tion. Bearings  of  this  type  are  much  used  for 
trolley  wheels  in  street-railway  practise. 

Wood,  especially  exceedingly  hard  wood,  such 
as  lignum  vitae,  boxwood,  etc.,  is  not  without  merit 
for  plain-bearing  surfaces  in  certain  situations. 
The  thrust  blocks  for  taking  the  propeller  thrust 
in  motor  boats  and  even  in  large  steam  vessels 
often  are  made  of  lignum  vitae,  lubricated  with 
water,  such  construction  proving  a  means  of  escap- 
ing the  problems  of  rusting  and  leakage  that  are 
likely  to  appear  when  it  is  attempted  to  use  bear- 
ings of  other  types  and  keep  them  supplied  with 
oil. 

Vulcanized  Fiber  makes  a  fair  bearing  material 
when  provided  in  sufficient  area  and  properly 
lubricated.  In  at  least  one  instance  of  a  supposedly 
well  designed  modern  automobile  fiber  thrust 
bearings  are  used  behind  the  bevel  gears  com- 
municating with  the  final  drive  to  the  rear  axle. 

FINISH  OF  PLAIN  BEAEINGS 

Of  fundamental  importance  in  the  successful 
use  of  plain  bearings  is  the  accuracy  of  finish, 
which  is  second  in  importance  only  to  the  matters 
of  proper  material  and  sufficient  size. 

Areas  of  plain  bearings  usually  are  figured  on 
the  basis  of  the  " projected  area",  as  suggested  by 
the  dotted  rectangle  a  &  c  d,  Figure  154,  this  rec- 


BEARINGS  345 

tangle  being  equivalent  to  a  cross  section  of  the 
center  of  the  shaft  within  the  bearing.  The  pro- 
jected area  must  be  of  sufficient 
surface  to  carry  the  load  consid- 
ered permissible  with  the  type  of 
bearing  material  used.  For  long- 
lived  babbitt  bearings  the  load 


per  square  inch  of  projected  area      projected  Area  of 

,         TT  .  J.-M  j.cj.  plain  Bearing. 

should  not  materially  exceed  forty 
pounds.  With  steel-bushed  piston-pin  bearings 
the  load  may  run  as  high  as  eight  hundred  pounds 
to  the  square  inch,  though  such  loading  does  not 
prove  conducive  to  slow  wear  and  long  life. 
Scraping  plain  bearings  is  necessary  in  all  cases 
where  babbitt,  bronze,  brass,  or  similar  materials 
are  used.  It  is  a  means  of  giving  a  more  perfect 
fit  to  the  shaft  than  is  possible  by  mere  turning  or 
reaming,  and  in  the  machine  shop  is  technically 
known  as  " spotting  in",  from  the  fact  that  the 
shaft  is  tested  in  the  bearing  many  times  in  the 
course  of  the  operation,  being  coated  after  each 
scraping  with  a  light  wash  of  Prussian  blue,  which 
rubs  off  on  the  high  spots  in  the  bearing  and  thus 
indicates  the  places  that  require  to  be  scraped 
down.  Commencing  with  a  babbitt  bearing  freshly 
cast  and  reamed,  and  contacting  with  the  shaft  at 
only  four  or  five  high  spots,  a  good  workman  will 
carry  this  process  of  spotting-in  a  bearing  until 
the  test  with  the  Prussian  blue  coating  shows  an 
great  number  of  minute,  closely-spaced  high  spots, 
indicating  so  even  a  distribution  of  the  load  over 


346 


VEHICLES  OF  THE  AIR 


FIGURE  155. — Ad  Just- 
ment  of  Plala  Bearing.  To 
tighten  the  bearing  one  or 
more  of  the  thin  liners  of 
sheet  metal  at  a  a  are  re- 
moved. 


the  entire  bearing  surface  that  wear  can  be  counted 
upon  to  result  with  almost  perfect  uniformity. 

Adjustment  of  plain  bear- 
ings is  generally  effected  by 
placing  in  or  removing  from 
the  space  a  a,  Figure  155,  be- 
tween the  two  bearing  cups, 
" shims"  of  thin  sheet  metal. 
The  lubrication  of  a  plain 
bearing  must  be  well  provided  for,  and  is  usually 
facilitated  by  grooving  and  drilling  the  bearing 
surfaces  to  spread  the  lubricant. 

MISCELLANEOUS  BEARINGS 

Cone  bearings,  of  the  type  illustrated  in  Figure 
156,  are  much  used  in  very  light 
machinery  generally  and  in  deli- 
cate instruments,  in  which  they 
prove  light-running,  fairly  du- 
rable, and  especially  meritorious 

J  FIGURE    156.— Cone 

in  that  they  permit  such  close  ad-  Bearing. 

justment  as  practically  to  eliminate  all  end  move- 
ment from  the  shaft. 


FIGURE  157. — Bleriot  XI  in  Flight.     This  is  the  monoplane  that  crossed  the  English  Channel. 


FIGURE  158. — Bleriot  XII  in  Flight.     This  monoplane  carries  three  passengers. 


CHAPTER  NINE 

LUBRICATION 

For  mechanisms  that  must  be  quite  light  and 
yet  subjected  to  a  maximum  possible  duty,  as  is 
the  case  with  practically  every  element  of  the 
power  plant  of  a  flying  machine,  it  is  a  most  press- 
ing necessity  that  constant  and  adequate  lubrica- 
tion be  automatically  provided  for  every  bearing, 
so  that  unfailing  functioning  is  reasonably  assured 
with  a  minimum  of  attention. 

Haphazard  methods  of  lubrication,  which  can 
be  made  to  serve  in  automobiles  and  other  mechan- 
isms, should  under  no  circumstances  be  tolerated 
in  the  design  of  an  aeronautical  power  plant,  in 
which  the  lubrication  must  be  regarded  as  one  of 
the  most  important  elements  of  the  whole  device 
and  arranged  for  on  a  correspondingly  adequate 
basis. 

SPLASH  LUBRICATION 

Splash  lubrication,  in  which  the  oil  is  contained 
in  a  reservoir  or  pit  adjacent  to  the  surfaces  to  be 
lubricated,  and  splashed  thereon  by  the  movement 
of  parts,  is  a  common  and  very  successful  method 
of  lubricating  certain  types  of  machinery,  being 
most  particularly  applicable  to  the  piston  and 
cylinder  walls  of  internal-combustion  engines, 
enclosed  gears,  etc. 

347 


348  VEHICLES  OF  THE  AIR 

In  many  well-known  types  of  automobile  en- 
gines the  connecting-rod  and  crankshaft  bearings 
are  lubricated  by  the  periodic  dip  of  the  big  end 
of  the  connecting  rod  into  oil  maintained  at  a  con- 
stant level  in  the  bottom  of  the  crankcase,  while 
in  at  least  one  well-known  make  a  trough-like 
groove  kept  full  by  the  splash  from  the  connecting- 
rod,  and  located  around  the  lower  end  of  a  cylinder 
so  that  the  edge  of  the  piston  dips  into  it  at  the 
bottom  of  each  stroke,  is  found  to  render  the  lubri- 
cation of  the  cylinder  walls  more  positive  than 
when  dependence  is  placed  solely  upon  the  splash. 

Spoon-like  extensions  from  the  lower  ends  of 
connecting  rods,  communicating  with  both  crank- 
pin  and  piston-pin  bearings,  are  in  some  circum- 
stances found  to  distribute  the  oil  better  than  is 
the  case  with  most  splash  systems. 

It  is  a  merit  of  splash  lubrication  that  it  auto- 
matically stops  and  starts  with  stopping  and  start- 
ing of  the  mechanism,  and  thus  is  always  fairly 
dependable,  but  it  has  the  fundamental  fault  that 
it  is  a  3/stem  of  re-using  the  lubricant,  the  oil 
being  supplied  in  measured  charges  of  considerable 
quantity  and  utilized  through  a  period  of  progres- 
sive deterioration.  When  it  no  longer  serves  its 
purpose  it  is  replaced  or  admixed  with  fresh  oil. 

KING  AND  CHAIN  OILERS 

Small  rings  or  chains  hanging  upon  a  shaft  and 
dipping  into  small  oil  pits  placed  at  suitable  points 
constitute  a  very  reliable  means  of  splashing  or 


LUBRICATION 


349 


taking  up  a  small  but  steady  flow  of  oil  to  find  its 

way  into  the  adjacent  bearings. 

Another  type  of  ring 
oiler,  much  used  for  the  lu- 
brication of  crankpins,  is 
that  pictured  in  Figure  159, 
in  which  a  is  the  ring,  fas- 
tened to  the  shaft  6  and  dip- 
ping below  the  oil  c,  so  that 
oil  flowing  into  the  groove  d 
is  there  held  centrifugally 
until  it  escapes  through  the 
hole  e,  connecting  with  the 

FIGURE  159. — Ring  Oiler  on  . 

Crankshaft.      The    ring    a,    by      hollOW  pin  /  . 


dipping    into    c,    picks    up    a 
small    quantity    of    oil    in    its 

frooved  edge  d,  in  which  it  is 
eld  by  the  rotation  of  the 
crankshaft  b  until  it  is  thrown 
centrifugally  through  the  hole 
e  to  the  crankpin  bearing, 
whence  it  finds  its  way  by 
the  pipe  f  to  the  piston-pin 
bearing. 


GRAVITY  LUBRICATION 


Gravity  lubrication,  in 
which  the  flow  of  oil  is  main- 
tained through  communicat- 
ing pipes  from  a  tank  located  above  the  bearing  or 
bearings,  is  exceedingly  simple  and  possesses  the 
virtue  of  always  supplying  fresh  oil  to  the  wearing 
surfaces,  the  oil  as  fast  as  it  is  used  draining  away, 
directly  to  the  ground  or  into  a  sumpor  pan  which 
can  be  emptied  at  intervals. 


OIL  CUPS 


Oil  cups,  placed  directly  over  the  bearings  they 
feed,  are  probably  the  simplest  and  commonest 
form  of  gravity  lubrication.  They  usually  are 
provided  with  some  sort  of  adjustable  drip  feed, 
with  a  sight  glass  to  inspect  the  rate  of  drip. 


350  VEHICLES  OF  THE  AIR 

RESERVOIR  SYSTEMS 

Keservoir  systems,  with  a  single  reservoir  con- 
nected by  a  plurality  of  leads  with  the  different 
bearings,  are  the  most  elaborate  forms  of  gravity 
lubrication,  and  usually  are  provided  with  sight 
feeds  and  means  for  regulating  the  flow  of  oil 
through  the  different  pipes. 

Like  all  forms  of  gravity  lubrication  these  sys- 
tems have  the  objection  that  the  pipes  may  become 
clogged  and  thus  cease  to  feed  corresponding  bear- 
ings, with  prompt  overheating  and  failure. 

FORCED  LUBRICATION 

Forced  lubrication,  by  which  the  lubricant  is 
sent  to  the  bearings  under  pressure,  is  in  its  best 
forms  the  most  reliable  and  meritorious  system 
possible,  because,  while  possessing  the  reliability 
of  splash  lubrication,  it  is  a  system  of  feeding  fresh 
lubricant  under  conditions  that  may  be  so  arranged 
as  to  avoid  the  possibility  of  stopped  pipes. 

PRESSURE  FEED 

One  of  the  simplest  forms  of  forced  lubrication 
involves  the  use  of  a  single  reservoir  with  a  number 
of  leads,  much  the  same  as  in  the  just-described 
reservoir  system  for  gravity  feeding  but  with  this 
difference — that  air  or  exhaust-gas  pressure  is 
maintained  to  deliver  the  lubricant,  so  as  to  afford 
greater  assurance  of  positive  feeding  than  is  had 
with  gravity  alone.  Nevertheless,  stoppage  of  one 
of  a  number  of  leads  is  likely  to  go  undetected,  the 
pressure  being  relieved  by  a  greater  flow  of  oil 
through  other  leads. 


FIGURE   162. — Koechlin   Monoplane   in   Flight. 


FIGURE  163.— Wright  Machine  on  Starting  Rail.  The  starting  rail  is  at  in,  n  is  the 
connection  of  the  rope  by  which  the  starting  impulse  is  given,  f  are  the  runners,  h  is  the 
elevator,  o  is  the  elevator  control  rod,  i  is  the  rudder,  and  I  is  one  of  the  steadying  planes 
peculiar  to  this  machine. 


FIGURE    164.— Bleriot   Alighting   Gear.     The   wheels   g   g,   upon   striking   the   ground    are 
ushioned  in  their  upward  movement  by  the  rubber  springs  s  s. 


LUBRICATION 


351 


SINGLE  PUMPS 

Single  pumps  for  forcing  a  continuous  flow  of 
oil  over  bearings  or  through  systems  of  leads,  the 
oil  usually  being  pumped  from  a  sump  or  pit  in  the 
crankcase  or  the  like,  are  found  very  satisfactory 
for  engine  lubrication,  though  as  a  special  safe- 
guard against  breakdown  the  circulating  system 
should  have  a  loop  with  a  glass  sight  feed  placed 
within  view  of  the  operator. 

MULTIPLE  PUMPS 

One  of  the  most  reliable  of  all  lubricating  sys- 
tems is  that  in  which  oil  is  sent  from  a  reservoir 
through  a  plurality  of  leads,  one 
to  each  bearing,  by  a  corre- 
sponding plurality  of  small  in- 
dividual pumps  each  admitting 
of  adjustment  to  vary  the  indi- 
vidual feed  and  capable  of 
working  against  high  enough 
pressure  to  insure  the  clearing 
out  of  any  possible  obstruction 
that  may  pass  into  the  pipes. 
Such  systems  of  forced  lubrica- 
tion are  extensively  used  in  the 
power  plants  of  the  best  automobiles,  and  for  fly- 
ing-machine power  plants  prove  similarly  superior. 

A  typical  force-feed  lubricator  is  illustrated  in 
Figure  160,  in  which  a  is  the  reservoir,  6  6  &  are 
the  leads,  c  c  c  are  adjustments,  and  d  d  d  are  the 
individual  sight  feeds  by  means  of  which  imperfect 
operation  or  failure  can  be  instantly  detected  and 
remedied. 


FIGURE  160.  —  Force- 
Feed  Lubricator.  The 
pipes  leading  to  the  dif- 
ferent bearings  are  at 
b  b  &,  adjustment  of  the 
flow  through  these  pipes 
is  by  the  thumbscrews 
ceo,  and  the  rate  of  the 
flow  is  shown  by  the 
sight  feeds  ddd. 


352  VEHICLES  OF  THE  AIR 

GEEASE  CUPS 

Grease  cups,  while  similar  to  oil  cups,  are  prop- 
erly systems  of  forced  lubrication  in  that  they  are 
filled  with  grease  or  non-fluid  oil  capable  of  being 
forced  out  by  screwing  down  the  top.  Grease  cups 
are  very  reliable  because  while  designed  primarily 
to  have  occasional  attention  they  will  neverthe- 
less feed  automatically  by  gravity  in  the  case  of 
an  overheated  bearing,  which  thus  may  take  care 
of  itself  by  melting  the  contents  of  the  grease  cup 
and  so  causing  them  to  flow  down  without  forcing. 

LUBRICANTS 

Suitable  lubricants  for  aeronautical  power 
plants  embrace  a  considerable  range  of  liquid  and 
solid  substances,  a  comparatively  small  number  of 
which,  however,  are  found  really  superior. 

MINERAL  OILS 

Mineral  oils,  derived  from  the  distillation  of 
petroleum,  are  almost  universally  used  for  the 
lubrication  of  the  heating  surfaces  in  gas  engines, 
being  capable  of  withstanding  temperatures  as 
high  as  600°  F.  and  800°  F.  without  giving  off 
ignitable  or  combustible  vapors.  Mineral  oils  also 
are  suitable  for  the  lubrication  of  gears,  plain 
bearings,  etc. 

Vaseline  is  a  petroleum  grease  that,  with  or 
without  admixture,  is  found  exceedingly  valuable 
for  lubricating  gears,  ball  bearings,  etc. 

Miscellaneous  mineral  lubricants  are  used  in 
great  number,  in  a  great  variety  of  combinations, 


LUBRICATION  353 

and  it  is  unfortunately  a  fact  that  the  composition 
of  many  of  these  is  dictated  by  commercial  rather 
than  by  technical  requirements,  for  which  reason 
it  behooves  the  user  of  a  high-grade  aeronautical 
engine,  ball  bearings,  or  other  delicate  mechanism, 
to  use  the  most  critical  judgment  in  discriminating 
between  the  different  preparations  marketed  for 
the  purpose,  altogether  too  many  of  which  are  very 
far  from  being  of  the  highest  quality.  Probably 
the  best  policy  is  to  patronize  only  the  most  repu- 
table dealers,  whose  integrity  and  commodities  are 
both  to  be  relied  upon. 

VEGETABLE  OILS 

Some  vegetable  oils  are  of  excellent  quality  for 
the  lubrication  of  some  types  of  bearings. 

Castor  Oil,  for  light  spindles  and  for  axles  not 
revolving  at  too  high  speeds,  is  excellent,  and  this 
oil  has  been  used  with  considerable  success,  with 
or  without  an  admixture  of  mineral  oil,  for  the 
lubrication  of  the  close-fitting  pistons  in  racing 
automobile  engines.  Used  for  this  purpose  it  tends 
to  cause  a  considerable  amount  of  carbonization, 
but  if  fed  in  sufficient  quantities  it  invariably 
relieves  friction  and  facilitates  smooth  operation 
in  a  degree  almost  impossible  to  attain  with  even 
the  lightest  and  best  of  mineral  oils. 

Olive  Oil,  suitably  treated  and  refined,  is  almost 
absolutely  non-drying,  for  which  reason  it  is  a 
preferred  ingredient  in  oils  for  fine  watches  and 
delicate  instruments. 


354  VEHICLES  OF  THE  AIR 

ANIMAL  OILS 

Sperm  Oil,  from  the  blubber  of  the  sperm  whale, 
is  considered  by  mechanical  experts  to  be  the  best 
of  all  lubricants  for  light  machinery,  such  as  sew- 
ing machines,  phonographs,  etc.,  and  undoubtedly 
will  find  more  or  less  application  in  aeronautical 
mechanisms. 

Tallow,  while  an  engineer  of  experience  might 
first  be  inclined  to  regard  it  as  totally  unsuitable 
for  the  lubrication  of  heated  surfaces,  is  neverthe- 
less found  to  be  the  only  satisfactory  lubricant  for 
the  cylinders  and  pistons  used  in  type-casting  ma- 
chines for  pumping  molten  type  metal.  This  fact 
might  seem  to  indicate  a  possibility  for  it  even  in 
the  field  of  internal-combustion  engine  lubrication. 
As  a  component  of  various  greases  for  gear  and 
other  lubrication,  tallow  fills  a  recognized  place. 
Most  of  the  solid  compounds  used  for  the  lubrica- 
tion of  bicycle  and  automobile  chains  are  an  admix- 
ture of  tallow  and  graphite,  and  are  best  applied 
by  being  melted,  and  the  chain  soaked  in  the  fluid. 

MISCELLANEOUS  LUBRICANTS 

In  this  category  fall  such  solids  as  finely- 
divided  graphite,  mica,  asbestos,  and  plumbago, 
all  of  which  tend  to  reduce  friction  by  filling  up 
the  minute  inequalities  that  can  be  microscopically 
proved  to  exist  in  the  most  perfectly  finished 
surfaces.  Graphite  is  generally  considered  far 
superior  to  the  others. 

Water  has  been  mentioned  (see  Page  344)  as  a 
lubricant  for  wood  thrust  bearings.  Soapsuds  is 


LUBRICATION  355 

recognized  by  engineers  to  be  without  a  superior 
for  cooling  and  lubricating  certain  types  of  plain 
bearings  under  certain  peculiar  conditions  of 
overheating. 

Kerosene,  while  not  commonly  regarded  as  a 
lubricant,  has  considerable  lubricating  qualities, 
and  for  light  shafts  and  spindles  can  be  made  to 
serve  the  purpose  very  effectively.  Even  in  gas 
engines  periodic  dosings  of  kerosene,  preferably 
fed  through  the  carbureter,  are  with  automobile 
experts  a  recognized  means  of  limbering  up  the 
mechanism,  serving  the  double  purpose  of  thin- 
ning used  oil  to  a  better  lubricating  body  and  of 
cutting  deposits  of  carbon. 


CHAPTER  TEN 

STARTING  AND  ALIGHTING 

The  problems  of  starting  and  alighting  with 
flying  machines  may  be  considered  to  apply  chiefly 
to  flying  machines  of  the  aeroplane  type,  since  bal- 
loons, helicopters,  and  ornithopters  do  not  require 
special  starting  or  alighting  appliances. 

But  for  the  aeroplane,  which  flies  by  means 
closely  analogous  to  the  means  employed  by  soar- 
ing birds,  the  necessity  for  some  sort  of  starting 
and  alighting  gear  or  device  is  apparent.  Even 
the  birds  do  not  escape  this  necessity,  small  birds 
making  their  initial  rise  into  the  air  by  one  or 
more  hops,  and  larger  birds  being  compelled  to 
drop  from  an  eminence  or  to  make  a  considerable 
run  on  the  ground — it  being  an  interesting  but  well 
established  fact  that  the  condor  and  the  California 
vulture,  the  largest  flying  birds  known,  can  be 
safely  imprisoned  in  a  small  pen,  open  at  the  top, 
but  with  sides  sufficiently  high  to  require  a  rather 
steep  angle  of  ascent. 

For  these  reasons,  already  suggested  in  the 
introduction  to  this  work  (see  Page  35),  as  the  suc- 
cessful flying  machine  comes  more  and  more  into 
practical  use  it  will  reasonably  come  to  be  regarded 
quite  natural  for  aerial  vehicles  to  require  for  their 
utilization  the  provision  of  special  landing  places 

356 


STARTING  AND  ALIGHTING  357 

and  starting  devices,  just  as  it  is  commonplace  for 
docks  to  be  provided  for  water  craft  and  stations 
for  railway  trains.  Also,  as  is  remarked  on  Page 
35,  it  probably  is  a  wholly  erroneous  idea  of  the 
factors  of  the  situation  to  suppose  that  aeroplanes 
are  proposed  or  will  be  used  for  urban  travel,  such 
as  must  require  their  starting  from  or  alighting  in 
the  streets  of  cities,  or  even  the  roofs  of  buildings — 
though  it  is  rather  more  probable  that  the  latter 
may  in  time  come  to  be  utilized  to  a  limited  extent. 
But  a  more  likely  provision  will  be  that  of  large 
cleared  areas  in  the  suburbs  of  towns,  permitting 
suburban  flying  between  these  areas  and  leaving 
the  problems  of  strictly  urban  transportation  to 
other  than  aerial  vehicles. 

STARTING  DEVICES 

A  very  logical  though  not  closely-drawn  dis- 
tinction can  be  made  between  starting  devices  and 
alighting  gears,  the  first  being  not  necessarily,  at 
any  rate  in  all  its  elements,  a  permanent  part  of  an 
aerial  vehicle,  whereas  an  alighting  gear  is  neces- 
sarily a  part  of  the  machine.  The  distinction  is 
complicated,  however,  by  the  fact  that  in  some 
machines  the  same  wheels  or  other  devices  serve 
both  as  starting  and  alighting  gears. 

For  these  reasons  it  will  not  be  attempted 
herein  to  draw  the  lines  between  classifications  too 
closely,  it  being  more  important  to  give  proper 
consideration  to  the  different  devices  that  have 
been  found  most  satisfactory  and  that  appear  the 


358  VEHICLES  OF  THE  AIR 

most  promising  for  the  effective  launching  and 
safe  landing  of  practical  air  craft. 

WHEELS 

The  simplest  and  most  widely  used  starting  de- 
vice is  the  wheel,  the  Santos-Dumont,  Voisin,  Cur- 
tiss,  Farman,  E.  E.  P.,  Antoinette,  Bleriot,  and 
many  other  successful  modern  biplanes  and  mono- 
planes all  being  provided  with  bicycle  or  motor- 
cycle wheels,  which  often  are  used  also  as  alighting 
gears — to  which  end  they  are  almost  without 
exception  fitted  with  spring  and  cushioning  devices 
to  take  up  the  shock  of  an  abrupt  encounter  with 

the  earth. 

BAILS 

The  use  of  rails  to  provide  smooth  tracks  for 
launching  aeroplanes  probably  originated  with 
Henson  in  1842,  at  which  time  he  employed  them 


FIGUBE  165. — Wright  Starting  System. 


in  an  attempt  to  launch  the  machine  referred  to 
on  Page  155.  Eails  were  then  used  by  Maxim,  as  a 
course  upon  which  to  start  and  test  his  wonderful 
but  unsuccessful  machine  (described  on  Page  156), 
which  lifted  itself  on  July  31, 1894.  The  next  use 


STARTING  AND  ALIGHTING  359 

of  rails  was  in  the  catapult-like  launching  device 
employed  by  Langley  in  his  trials  over  the  Potomac 
River  during  the  years  1896  to  1903,  inclusive. 

The  most  modern  and  practically  the  only  suc- 
cessful use  of  rail  launching  devices  is  in  conjunc- 
tion with  the  modern  Wright  machines,  which  are 
run  an  initial  distance  of  from  70  to  125  feet,  bal- 
anced on  a  tiny  two-wheeled  truck,  on  a  single 
crude  wooden  rail,  about  eight  inches  high  and 
faced  with  strap  iron.  This  arrangement  is  more 
fully  described  on  Page  362,  and  is  illustrated  in 
Figures  163,  165,  and  166. 

FLOATS 

Floats,  in  the  form  of  boat-like  hulls,  have  been 
to  some  extent  used  in  experimenting  with  aero- 
planes over  water  surfaces,  and  appear  to  present 
possibilities  of  practical  development.  The  use  of 
light  racing  shells,  which  are  capable  of  carrying 
from  five  to  nine  men  totaling  from  800  to  1,600 
pounds,  and  which  weigh  from  thirty  to  fifty 
pounds,  appears  to  be  the  most  promising  line  of 
development,  though  waterproof  fabric  floats  can 
be  made  exceedingly  light  for  a  given  sustaining 
effect. 

Undoubtedly,  just  so  soon  as  some  means  is 
devised  of  permitting  aeroplanes  to  start  from  and 
alight  upon  water  surfaces  without  exterior  aid, 
trans-aquatic  journeys  will  become  practicable 
with  almost  absolute  safety  even  with  present 
machines.  The  hydroplane  type  of  boat  hull, 
which  skims  over  the  surface  of  the  water  rather 


360  VEHICLES  OF  THE  AIR 

than  plowing  through  it,  in  many  respects  appears 
to  be  the  ideal  form  of  float  for  water-traversing 

aeroplanes. 

EUNNEES 

Runners,  besides  having  been  used  successfully 
by  the  Wrights  in  starting  over  wet  grass  under 
the  thrust  of  the  propellers,  also  have  been  used 
in  starting  from  ice — frozen  lake  surfaces — in  the 
work  of  the  Aerial  Experiment  Association.  Their 
most  conspicuous  merits,  however,  are  as  alighting 
rather  than  as  starting  devices.  (See  Page  370. ) 

THE  STAETING  IMPULSE 

It  being  necessary  with  most  modern  aero- 
planes to  make  a  shorter  or  longer  run  on  the 
ground  or  on  rails  before  sufficient  sustention  is 
secured  to  rise  in  the  air,  the  question  of  securing 
the  necessary  starting  impulse  becomes  one  of 
some  moment,  and  it  is  evident  at  the  outset  that 
the  solution  can  be  reached  in  any  one  of  a  number 
of  different  ways. 

To  maintain  an  aeroplane  in  flight  no  very 
great  thrust  or  pull,  as  the  case  may  be,  is  required, 
the  amount  of  this  thrust  or  pull  being  probably 
from  100  pounds  to  250  pounds  in  the  different 
machines  that  have  proved  most  successful  so  far — 
though  there  is  reason  for  expecting  that  much 
lower  tractive  forces  will  suffice  as  head  and  aero- 
dynamic resistances  come  to  be  lowered — but  for 
securing  the  rapid  rate  of  acceleration  required  to 
reach  a  sustaining  speed  with  only  a  short  run,  a 
much  greater  thrust  is  essential. 


I         .4 


FIGURE    166.— Wright   Machine   on    Starting   Rail,    with    Starting   Derrick   in    the   Back" 


round 


r 


FIGURE   168.— Rougier's   Voisin    Rising  from    Starting   Ground. 


STARTING  AND  ALIGHTING  361 

Propeller  Thrust,  upon  which  dependence  is 
placed  to  maintain  modern  aeroplanes  in  motion, 
also  is  used  in  most  of  those  with  wheeled  starting 
and  alighting  gears  to  produce  the  initial  run  on  the 
ground,  but  in  most  of  the  machines  to  which  this 
method  is  applied  it  has  not  been  found  possible 
to  get  into  the  air  with  runs  of  less  than  from  200 
to  400  feet  over  fairly  good  ground.  This  distance 
can  be  kept  to  a  minimum  by  holding  the  machine 
until  the  propeller  is  at  full  speed,  either  by  a  brake 
or  by  the  efforts  of  assistants.  Another  possible 
scheme  might  be  the  use  of  a  sprag-like  claw  to 
catch  in  the  ground,  until  it  were  desired  to  release 
the  machine.  In  Figure  164  it  will  be  noted  that 
the  wheels  of  the  machine  are  blocked. 

Starting  solely  by  its  thrust,  the  propellers 
have  even  been  employed  successfully  for  starting 
with  the  Wright  machine,  without  the  rail,  the 
aeroplane  being  simply  slid  on  its  runners  over  wet 
grass,  but  in  this  case  an  initial  run  of  five  hun- 
dred feet  was  found  necessary  before  the  machine 
altogether  left  the  ground.  In  this  connection, 
however,  it  is  interesting  to  reflect  that  no  such 
duty  devolves  upon  the  propeller  as  would  be 
involved  in  dragging  the  full  weight  of  the  machine 
over  the  ground  for  the  entire  distance,  with  it 
resting  solidly  upon  its  runners.  The  reason  for 
this  is  that  as  soon  as  any  headway  whatever  is 
attained,  there  is  a  corresponding  measure  of  lift 
which  proportionately  reduces  the  weight  resting 
upon  the  runners — the  weight  thus  supported 
gradually  reducing  from  the  entire  weight  of  the 


362  VEHICLES  OF  THE  AIR 

vehicle  at  the  start,  to  an  infinitely  small  percent- 
age of  this  just  before  lifting  from  the  ground. 

An  advantage  of  the  propeller  in  affording  the 
starting  impulse  is  that  its  thrust  is  highest  when 
the  vehicle  speed  is  lowest — at  which  time  the  need 
for  high  thrust  is  greatest. 

Dropped  Weights,  operated  in  small  starting 
derricks,  the  pylons  of  the  French,  are  in  some 
respects  an  excellent  means  of  securing  the  initial 
impulse,  though  they  are  so  far  employed  only 
with  the  Wright  machines.  In  the  Wright  starting 
device,  shown  in  Figures  165  and  166,  the  tower  is 
an  extremely  simple  and  inexpensive  one  of  pyr- 
amidal form,  built  of  four  main  timbers  each  about 
twenty-five  feet  long  and  two  inches  square, 
lightly  braced  by  three  horizontal  frames  and 
diagonal  wire  stays.  The  weight,  about  fourteen 
hundred  pounds  of  cast  iron  disks  (a  can  of  earth 
or  stone  has  been  suggested  as  perfectly  suitable 
for  emergency  use)  is  attached  to  one  of  two  pul- 
ley blocks,  the  other  of  which  is  suspended  in  the 
apex  of  the  tower,  the  rope  passing  around  the 
sheaves  a  sufficient  number  of  times  to  provide  a 
three-to-one  relation  between  the  movement  of  the 
weight  and  the  movement  of  the  aeroplane  along 
the  starting  rail. 

Disregarding  friction  losses  in  the  sheaves,  the 
rope,  which  passes  down  to  the  bottom  of  the 
tower,  forward  to  and  around  a  pulley  towards  the 
front  end  of  the  rail,  and  thence  back  to  the  aero- 
plane, exerts  a  pull  of  about  450  pounds,  with  a 
rate  of  acceleration  about  in  relation  to  the  law 


STARTING  AND  ALIGHTING  363 

of  falling  bodies,  which  of  course  governs  the  fall 
of  the  weight.  To  the  pull  of  the  weight  is  added 
the  thrust  of  the  propellers,  which  are  set  in 
motion  before  the  machine  is  released  for  its  start 
along  the  rail.  The  propellers  take  up  the  entire 
work  of  propelling  the  machine  when  some  fifty  or 
sixty  feet  of  the  rail  are  traversed,  the  weight  not 
accelerating  the  machine  clear  to  the  end  of  the 
rail. 

At  the  limit  of  the  weight-impelled  portion  of 
its  travel  along  the  rail,  the  rope  automatically 
unhooks  from  its  attachment  to  the  machine,  which 
promptly  thereafter  lifts  off  the  truck  on  which  it 
has  been  mounted  and  at  once  commences  free 
flight. 

Winding  Drums,  as  a  substitute  for  the 
dropped- weight  system  of  starting,  have  been  pro- 
posed by  a  number  of  experimenters.  In  a  patent 
issued  to  Octave  Chanute  the  principle  is  claimed 
of  locating  a  power-driven  winding  drum  on  a  con- 
veniently placed  truck,  this  drum  connecting  by 
a  cable  with  the  aeroplane  in  such  manner  that  the 
cable  connections  can  be  thrown  off  by  the  opera- 
tor just  before  or  after  the  machine  leaves  the 
ground. 

In  a  starting  device  invented  by  the  writer  the 
principle  is  claimed  of  locating  a  winding  drum  on 
the  aeroplane  as  at  a,  Figure  167,  a  light  wire  cable 
running  from  this  drum  to  a  stake  driven  in  the 
ground.  By  providing  the  end  of  the  cable  with 
a  ball-like  or  flat  end  fixture,  arranged  so  that  it 
will  disengage  automatically  from  the  spherically- 


364  VEHICLES  OF  THE  AIR 

cupped  or  otherwise  peculiarly-formed  head  of  the 
stake  as  soon  as  it  pulls  up  at  a  vertical  enough 
angle  from  the  vehicle  passing  over  the  latter,  a 
very  effective  means  of  starting  is  provided.  The 
writer  prefers  to  make  the  drum  of  a  varying 
diameter  from  one  end  to  the  other  so  that  the 
desired  acceleration  is  secured  without  variation 


FIGURE  167. — Starting  by  Rope  Attached  to  Stake  and  Wound  in  on  Drum. 
The  drum,  which  may  be  friction-driven  from  the  engine,  winds  in  the  rope 
until  the  machine  is  nearly  over  the  stake.  Provision  can  be  made  for  auto- 
matic cessation  of  the  winding-  at  this  point,  so  that  the  rope  frees  itself 

making   the   drum   of 
>n  is  readily  provided. 


from   the   stake   as   the   machine   passes   over   it.      By   making   the   drum   of 
tapered  instead  of  cylindrical  form,  proper  accelerator 


in  engine  speed.  Also,  it  is  preferred  to  connect 
the  drum  with  the  shaft  by  a  friction  clutch,  but 
many  alternative  constructions  of  course  are  pos- 
sible. In  this  scheme  of  starting  it  is  required  to 
leave  a  stake  in  the  ground  each  time  a  start  is 
made,  but,  the  stakes  being  made  very  light,  pref- 
erably of  steel  tubing,  the  necessity  of  carrying 
along  a  few  is  not  a  serious  objection,  especially 
when  it  is  considered  that  even  in  a  machine  regu- 
larly equipped  with  such  a  starting  device  it  would 
be  brought  into  use  only  when  other  methods  of 
starting  could  not  be  employed. 

Inclined  Surfaces,  for  starting  aeroplanes  by 
the  action  of  gravity,  have  been  used  most  suc- 
cessfully by  Lilienthal,- the  Wrights,  and  some 
others.  They  constitute  one  of  the  simplest  of  all 
possible  means  of  starting  and  under  proper  con- 
ditions are  very  effective.  The  utilization  of  natu- 


STARTING  AND  ALIGHTING  365 

rally  sloping  ground,  either  alone  or  in  conjunction 
with  any  established  starting  means,  greatly  facili- 
tates starting.  The  Wrights  usually  endeavor  to 
lay  their  starting  rail  down  hill,  direction  of  the 
wind  permitting,  and  the  same  is  true  of  the  runs 
made  by  other  experimenters  on  wheeled-starting 
devices. 

LAUNCHING  VEHICLES 

This  term  is  applied  by  the  writer  to  a  class  of 
starting  mechanisms  that  have  been  more  exten- 
sively suggested  than  experimented  with.  By  it 
it  is  meant  to  refer  to  such  possible  methods  of 
starting  as  by  mounting  an  aeroplane  on  an  auto- 
mobile, rail  vehicle,  or  water  craft,  and  making  the 
initial  run  with  this  vehicle,  with  the  idea  that  the 
aeroplane  will  rise  into  free  flight  as  soon  as 
sufficient  speed  is  reached. 

Automobiles  might  easily  be  built  in  a  modified 
form  suitable  for  the  purpose  just  suggested — with 
a  rather  simple  car,  capable  of  the  necessary  speed 
on  good  ground  and  provided  with  a  substantial 
framework  rising  above  the  head  of  the  driver, 
upon  which  to  rest  the  aeroplane  without  any 
attachment  other  than  the  use  of  such  lugs  as 
might  be  necessary  to  keep  the  aeroplane  from 
sliding  off  backwards.  With  such  a  construction 
it  should  be  an  easy  matter  to  start  an  aeroplane 
in  the  air  by  a  short  run  over  any  suitable  surface. 

Railway  Cars  of  a  special  type — possibly  small 
gasoline  or  electrically-propelled  flat  cars — might 
readily  be  made  to  serve  the  same  purpose,  though 
in  this  case  the  necessity  for  a  track  is  an  objection 


366  VEHICLES  OF  THE  AIR 

because  it  is  desirable  always  to  have  the  aeroplane 
face  the  wind  when  leaving  the  ground. 

Boats,  in  several  types  of  motor  launches,  tor- 
pedo-boats and  torpedo-boat  destroyers,  and  fast 
cruisers  and  battleships,  possess  established  speeds 
well  in  excess  of  the  minimum  flying  speeds  of 
several  successful  modern  aeroplanes.  Conse- 
quently such  water  craft,  with  a  perfectly  clear 
deck  forward  upon  which  to  mount  suitably-de- 
signed aeroplanes,  by  running  into  the  wind  must 
constitute  quite  effective  means  of  launching  the 
aerial  vehicles.  Subsequent  alighting  upon  the 
water  would  be  perfectly  safe  with  proper  floats  as 
alighting  gears,  while  disappearing  cranes  would 
serve  excellently  to  hoist  the  aeroplanes  inboard 
for  reprovisioning  or  restarting. 

CLEAEED  AREAS 

No  matter  which  of  the  starting  and  landing 
methods  so  far  considered  is  to  come  into  ulti- 
mate prominence,  it  seems  impossible  ever  to 
escape  the  superior  desirability  of  cleared  areas 
from  which  to  start  and  upon  which  to  alight. 
Moreover,  such  areas  will  hardly  suffice  if  merely 
made  long  and  comparatively  narrow,  as  has  been 
often  suggested.  Apparently  they  must  be  cir- 
cular in  form,  so  that  alighting  or  starting  in  any 
direction  will  allow  sufficient  distance  for  neces- 
sary retarding  or  accelerating.  A  maximum  of 
500  feet  would  seem  to  be  the  distance  suitable  for 
most  present-day  machines,  this  distance  in  all 
directions  calling  for  a  cleared  circular  field  of 


STARTING  AND  ALIGHTING  367 

about  six  acres.  In  case  of  such  an  area  being  bor- 
dered by  trees  or  high  buildings,  such  as  might  not 
be  readily  passed  over  at  the  steepest  possible 
angle  of  ascent,  it  would  be  necessary  to  extend  the 
space  considerably  beyond  that  actually  required 
for  the  mere  run  on  the  ground.  The  possible  limit 
required  would  be  an  area  large  enough  to  permit 
circling  flight  over  it  until  sufficient  height  were 
attained  to  pass  over  the  highest  of  adjacent  ob- 
stacles. A  Voisin  aeroplane  starting  from  such  a 
field  is  shown  in  Figure  168. 

PACING  THE  WIND 

Facing  the  wind,  while  perhaps  not  an  absolute 
necessity,  certainly  is  a  most  desirable  condition  of 
starting  with  present  types  of  machines.  Obvi- 
ously, a  sustaining  surface  requiring  a  certain 
speed  through  the  air  before  it  can  lift  the  machine 
from  the  ground,  would  when  running  with  the 
wind  afford  less  actual  speed  through  the  air  than 
over  the  ground,  requiring  a  consequently  higher 
speed  over  the  ground  to  secure  the  necessary 
speed  through  the  air.  On  the  other  hand,  travel 
against  the  wind  adds  substantially  the  speed  of 
the  wind  to  the  ground  speed  of  the  vehicle,  with 
the  result  of  rendering  starting  in  a  moderate  wind 
easier  than  in  a  calm.  The  only  condition  under 
which  starting  in  the  wind  might  be  objectionable 
would  be  the  existence  of  a  gale  greater  in  speed 
than  the  maximum  flying  speed  of  the  aeroplane. 
This  might  cause  the  vehicle  to  be  thrown  back- 
wards with  more  or  less  force  against  the  ground 
or  any  neighboring  obstacle. 


368  VEHICLES  OF  TEE  AIR 

A  wind  from  one  side  is  particularly  objection- 
able in  starting,  as  it  tends  to  careen  the  machine 
over  even  before  it  is  in  flight,  and  therefore  must 
inevitably  result  in  disaster. 

Of  course,  once  flying  is  under  way  it  is  a  com- 
paratively simple  matter  to  turn  and  travel  in  any 
direction — with  the  wind,  against  it,  or  across  it. 

LAUNCHING  FROM  HEIGHT 

Dropping  a  machine  from  a  height  or  launching 
it  over  the  edge  of  a  cliff  or  building  bears  a  rather 
close  resemblance  to  the  means  of  starting  em- 
ployed by  many  birds,  whose  powers  of  flight  are 
such  that  they  unhesitatingly  plunge  from  cliffs, 
trees,  buildings,  etc.  In  artificial  constructions, 

d 


\<L 


FIGURE  169. — Blerlot  Starting  Device.  The  aeroplane  Is  hooked  by  the 
rope  6  to  the  pulley  c,  which  runs  along  the  rear  edge  of  the  pillar  a. 
By  starting  the  propeller  the  back  draft  of  air  thrown  under  the  wings  d  d 
IB  expected  to  lift  the  machine  until  c  runs  off  the  top  of  a. 

the  only  instance  of  the  successful  use  of  this 
scheme  was  its  employment  by  Professor  Mont- 
gomery in  his  experiments  in  California  in  1905, 
in  the  course  of  which  his  wonderful  glider  was 
released  with  safety  from  balloons  sent  to  heights 
as  great  as  4,000  feet.  Of  unsuccessful  attempts 
at  this  sort  of  launching,  possibly  the  most  recent 


FIGURE  173. — Elevating  Montgomery  Aeroplane  with  a  balloon,  in  California,  in  1905. 


STARTING  AND  ALIGHTING  369 

was  Langley's  ill-fated  launching  of  his  full  size 
machine  from  the  top  of  a  house  boat  over  the 
Potomac  Eiver  on  December  8, 1903.  Previous  to 
these  experiments  history  records  various  at- 
tempts of  individuals  whose  efforts  to  navigate  the 
air  more  than  once  involved  leaps  from  cliffs  and 
towers,  as  in  the  cases  mentioned  in  Chapter  15. 
Practically  all  of  these  resulted  in  more  or  less 
serious  mishap. 

In  gaging  the  practical  merits  of  this  scheme 
it  always  is  to  be  considered  that  should  an  aerial 
vehicle  be  launched  from  a  roof  or  tower,  and  sub- 
sequently prove  to  have  anything  seriously  wrong 
with  its  sustaining  elements,  the  consequence  could 
scarcely  fail  to  be  a  serious  disaster.  On  the 
other  hand,  in  launching  from  the  ground,  should 
the  machine  prove  not  to  be  in  proper  flying  con- 
dition it  would  be  likely  simply  to  fail  to  go  up. 

ALIGHTING  GEARS 

Alighting  gears,  while  in  many  machines  iden- 
tical with  the  starting  means,  are  not  so  in  all 
cases.  Nevertheless,  in  practically  all  present-day 
aeroplanes  that  are  started  on  wheels,  the  wheels 
also  are  used  for  alighting,  being  usually  mounted 
on  one  sort  or  another  of  shock  absorbers  as  has 
been  already  suggested  on  Page  358. 

WHEELS 

The  alighting  device  of  a  typical  modern  aero- 
plane is  very  well  illustrated  in  Figure  170.  In 
this  the  long  helical  springs  at  s  $  take  the  shock 


370  VEHICLES  OF  THE  AIR 

of  alighting,  the  wheels  gg  swinging  on  the 
linkages. 

The  Bleriot  alighting  gear,  shown  in  Figures 
118, 164,  and  171,  is  similar  to  the  foregoing  except 
in  it  pluralities  of  rubber  bands  are  used  in  place 
of  the  helical  springs,  being  found  both  lighter  in 
weight  and  less  likely  to  break  for  a  given  cush- 
ioning effect. 

With  wheels  used  as  alighting  gears,  several 
experimenters  have  provided  brakes  to  produce 
rapid  retardation  after  touching  the  ground.  Such 
a  brake  is  a  feature  of  the  Curtiss  machine.  (See 
Figure  228  and  Chapter  12. )  Another  unusual  fea- 
ture of  the  Curtiss  running  gear  is  the  total  absence 
of  any  sort  of  shock  absorber. 

KUNNEBS 

Runners  for  alighting  possess  the  advantage 
over  wheels  that  they  will  span  inequalities  of 
surface  that  must  inevitably  wreck  a  wheel,  as  is 
quite  evident  in  Figure  163.  They  also  consti- 
tute an  effective  brake  that  comes  into  perfectly 
gradual  and  most  effective  operation  as  soon  as  the 
weight  of  the  vehicle  commences  to  be  sustained 

upon  the  ground. 

FLOATS 

As  has  already  been  suggested  on  Page  359,  the 
use  of  floats  for  machines  intended  to  fly  over  water 
possesses  some  merits.  And,  of  course,  any  float 
that  will  suffice  to  hold  a  machine  up  well  enough 
to  make  a  start  from  the  water  must  also 
serve  very  satisfactorily  to  alight  upon.  Wilbur 


th,irr  17°'TTypical  Ali^ting  Gear.     In   this  the  upward   swing  of  the  wheels  g  u  on 

their  link  connections  is  cushioned  by  the  helical  springs  s  *. 


STARTING  AND  ALIGHTING  371 

Wright's  use  of  a  canvas  canoe  hull  attached  to 
the  understructure  of  his  machine  during  his 
flights  around  New  York  during  the  Hudson-Ful- 
ton celebration  is  significant  in  this  connection. 

MISCELLANEOUS 

Besides  the  more  or  less  distinctly  different 
types  of  starting  and  alighting  gears  so  far  tried, 
there  appears  to  be  considerable  progress  to  be  had 
from  experiments  with  various  combinations  of 
differing  individual  elements. 

For  example,  in  Figure  174  there  is  shown  the 
under  construction  of  the  recent  Farman  machines, 
in  which  the  wheels  gggg  are  used  for  the 
starting  run,  while  in  alighting  the  wheels  spring 
up  above  the  runner  level  from  the  shock  of  con- 
tact, so  that  the  runners  come  into  play  as  brakes 
and  protect  the  wheels  from  inequalities  of  surface. 

Superior  in  many  respects  to  the  two  foregoing 
would  appear  to  be  some  more  definite  scheme  of 
dropping  and  locking  the  runners  below  the  wheel 
level  and  of  raising  them  above  it,  as  conditions  of 
alighting  or  landing,  respectively,  might  require. 

In  considering  possible  combinations  of  start- 
ing and  alighting  elements,  it  appears  probable 
that  in  time  there  may  even  be  developed  starting 
and  alighting  gears  capable  of  starting  from  or 
landing  upon  any  reasonably  clear  space  of  land 
or  water,  without  recourse  to  special  constructions 
for  special  conditions. 


CHAPTER  ELEVEN 

MATERIALS  AND  CONSTRUCTION 

The  questions  of  structural  materials  and  meth- 
ods of  construction  are  among  the  most  vital  of  all 
that  the  aeronautical  engineer  has  to  face.  Every 
matter  of  safety  and  success  depends  directly  upon 
the  quality  and  reliability  of  the  materials  of 
which  the  machines  are  built,  and  the  ways  in 
which  these  materials  are  put  together. 

Fortunately  the  problem,  while  one  of  great 
difficulties,  is  also  possessed  of  important  compen- 
sating advantages.  It  is  becoming  more  and  more 
established  that  successful  flying  machines  require 
the  use  of  comparatively  little  metal,  and  especially 
of  little  metal  of  resistant  qualities  worked  into  in- 
tricate shapes.  The  result  is  that  flying-machine 
construction,  while  often  requiring  considerable 
painstaking  labor  does  not  particularly  require 
expensive  facilities,  and  therefore  stands  open  to 
a  greater  number  of  unhandicapped  amateur  ex- 
perimenters than  almost  any  other  field  of  engi- 
neering research  or  industrial  enterprise. 

Necessarily,  other  equipment  being  equal,  the 
engineers  most  certain  to  achieve  success  in  pio- 
neering this  new  field  will  be  those  who  prove  the 
most  widely  informed  and  resourceful.  For  these 
reasons  at  least  a  smattering  of  a  great  many 

372 


FIGURE  171. — Details  of  Bleriot  Monoplane.  This  is  one  of  the  earlier  machines  of  the 
"Bleriot  XI"  type,  and  is  provided  with  an  eight-cylinder,  water-cooled  motor,  with  radiator 
immediately  beneath  it.  The  wheels  g  g  and  the  rubber  springs  s  s  are  characteristic  of  the 
Bleriot  alighting  gear,  but  in  the  case  of  the  latter  the  multiplication  of  the  movement  as 
shown  in  this  view  by  passing  over  rollers  has  been  abandoned. 


L  AVIATION 


FIGURE    172. — Alighting    Gear    of    Paulhan's    Voisin.     The    wheel    <j 
safeguard  against  undue  forward  inclination  of  the  machine  in  landing. 


prow    is    a 


MATERIALS  AND  CONSTRUCTION       373 

different  trades  is  likely  to  be  prolific  in  suggested 
ways  of  accomplishing  things. 

Because  of  the  great  need  for  a  comprehensive 
view  of  and  assimiliation  from  all  fields  of  engi- 
neering, it  seems  proper  here  to  call  attention  to 
various  examples  of  construction  that  have  been 
either  overlooked  or  have  failed  to  gain  the  con- 
sideration their  merits  demand.  Certainly  no 
worker  in  aeronautics  can  afford  to  be  unfamiliar 
with  the  wonderfully  light,  strong,  and  durable 
sled  and  boat  constructions  that  the  Eskimo 
achieves  with  bits  of  wood,  sinew  lashings,  and  skin 
coverings;  or  with  the  almost  perfect  craftsman- 
ship displayed  in  the  manufacture  of  the  primitive 
weapons  of  many  savage  races — not  to  forget  the 
more  enlightened  workmanship  of  the  modern 
bicycle  or  automobile  builder. 

WOODS 

Not  without  a  considerable  basis  of  fact  it  has 
been  asserted  that  the  flying  machines  of  the  future 
will  be  built  in  the  carpenter  shops  of  the  future, 
for  wood  is  by  far  the  most  utilized  material  in  all 
successful  fliers.  For  wing  bars  and  ribs,  runners 
and  running  gears,  frames,  braces,  and  the  like, 
wood  seems  as  serviceable  and  indispensable  as  it 
is  for  the  rims  of  bicycle  wheels,  besides  which  it  is 
cheap  and  easily  worked. 

It  is  not  generally  appreciated,  even  by  many 
engineers,  that  certain  woods  constitute  almost  the 
strongest,  most  reliable,  and  most  durable  of  all 


374  VEHICLES  OF  THE  AIR 

structural  materials,  the  best  qualities  of  selected 
timber  being,  weight  for  weight,  close  rivals  in 
sheer  strength — compressive,  tensile,  shearing,  and 
even  torsional — with  all  metals  but  the  very  finest 
alloy  steels,  while  in  immunity  from  flaws  and 
uncertainty  in  regard  to  physical  properties,  woods 
are  even  superior  to  metals,  especially  when  well 
seasoned.  Unseasoned  woods  beside  being  heavy 
are  often  less  than  half  as  strong  as  the  same  tim- 
ber thoroughly  dry. 

Chemically  and  microscopically,  wood  is  a  mul- 
ticellular  structure  of  cellulose  with  a  pronounced 
longitudinal  grain,  affording  its  greatest  strength 
in  a  longitudinal  direction,  though  some  woods  are 
enough  tied  together  with  transverse  fibers  to  af- 
ford great  resistance  to  splitting.  This  resistance 
is  usually  from  one-tenth  to  one-twentieth  of  the 
tensile  strength  in  a  longitudinal  direction. 

Woods  are  commonly  divided  loosely  into  two 
classes — hardwoods  and  softwoods — though  there 
is  not  really  any  distinct  demarcation  between  the 
classes,  there  being  a  variety  of  qualities  so  great 
as  to  shade  by  imperceptible  gradations  from  the 
softest  to  the  hardest. 

HARDWOODS 

For  a  given  bulk  the  best  hardwoods  are  much 
stronger  than,  most  softwoods,  besides  generally 
possessing  qualities  of  tenacity  and  flexibility  that 
contrast  favorably  with  the  brittleness  of  some  of 
the  very  strongest  softwoods,  but  for  a  given 
strength  within  a  given  weight  rather  than  within 


FIGURE  174. — Alighting  Gear  of  Farman  Machine.     Note  the  runners  f  f  and  the  wheels  g  g. 


FIGURE  175. — Boat-like  Body  of  Antoinette  Monoplane.     This  machine,  which  is  equipped 
with  a  hundred  horsepower  motor,  will  run  on  the  land,  in  the  water,  and  in  the  air. 


FIGURE  176.— Alighting  Gear  of  Antoinette  Monoplane.  Most  of  the  weight  is  carried 
on  the  two  center  wheels  g  g,  with  the  spring-mounted  spherical  wooden  rollers  at  &  6  to 
balance  the  machine.  The  runner  /  is  an  additional  safeguard  against  shock  in  landing. 


MATERIALS  AND  CONSTRUCTION       375 

a  given  size,  a  few  of  the  softwoods  are  superior 
to  the  strongest  hardwoods. 

Applewood  is  in  its  best  qualities  a  remarkably 
fine  timber,  especially  for  service  in  which  great 
resistance  to  splitting  is  required.  For  this  reason 
it  is  much  sought  by  makers  of  handles,  chisel  and 
other  handles  made  of  applewood  being  almost  im- 
possible to  split  even  under  the  hardest  hammer- 
ing with  a  mallet.  The  difficulty  of  securing  large 
clean  pieces  undoubtedly  prevents  more  extensive 
use  of  this  wood.  For  flying-machine  propellers  it 
would  appear  to  possess  particular  merits. 

Ash  is  proved  second  only  to  hickory  in  its  use- 
fulness for  carriage  shafts,  ladders,  handles,  etc., 
but  though  it  strongly  resists  utter  breakage  it 
lacks  stiffness  and  therefore  is  best  when  pliability 
is  a  requisite.  The  foregoing  applies  especially  to 
white  ash — particularly  to  second-growth  timber. 
Black  ash  splits  easily  and  is  even  more  flexible, 
but  is  very  tough.  It  is  much  used  for  barrel  hoops, 
while  as  a  material  for  bows  every  archer  knows  it 
has  few  superiors.  It  is  also  applied  to  a  consider- 
able extent  in  the  manufacture  of  oars  and  paddles. 

Bamboo,  botanically  the  largest  of  all  grasses, 
grows  up  to  a  foot  in  diameter  and  120  feet  high  in 
some  of  its  200  or  more  varieties,  which  are  particu- 
larly plentiful  in  southern  Asia  and  South  America, 
and  its  marvelously  light,  elastic,  and  hard  hollow 
stems  are  used  the  world  over  for  everything  from 
fishing  poles  to  primitive  but  serviceable  bridges. 
Split  bamboo,  in  which  the  greater  strength  of  the 
silicious  surface  of  the  canes  is  most  favorably 


376 


VEHICLES  OF  THE  AIR 


FIOUKB  177. — Built-Up  Bamboo  Spar. 
At  a  and  o  are  shown  cross-sections  of 
the  spar  e,  glued  up  from  pieces  cut  a» 
•hown  at  &  and  d. 


placed  to  resist  stresses,  is  a  favored  construction 
for  fishing  poles,  and  should  readily  find  applica- 
tion to  flying  ma- 
chines once  the  de- 
mand is  created  (see 
Figures  177  and  180). 
In  rather  remark- 
able contradistinction 
to  other  woods,  bam- 
boo is  a  material  that 
becomes  less  valuable 
as  it  is  well  seasoned, 
natural  bamboo  poles 
as  large  as  two  inches 
in  diameter  or  over  almost  invariably  cracking  and 
splitting  longitudinally  as  they  become  well  dried 
out  with  age. 

Birch,  either  red  or  black,  is  among  the  most 
resistant  of  woods  to  splitting  and  is  very  fine 
grained  and  strong.  In  its  different  varieties  birch 
is  used  for  everything  from  articles  requiring  fine 
carving  to  ox  yokes,  saddle  trees,  etc.  The  bark 
of  the  common  birch,  used  by  the  Indians  for 
making  canoes,  baskets,  etc.,  is  a  very  light  and 
strong  material  that  might  conceivably  find  some 
application  in  flying-machine  construction. 

Boxwood  is  even  more  resistant  in  small  cor- 
ners and  edges  than  maple,  for  which  reason  it  is 
much  used  for  wood  carving.  Its  great  weight  is  a 
serious  objection  from  aeronautical  standpoints. 
Elm  has  a  rather  interwoven  grain  and  does  not 
split  easily,  but  though  very  strong  it  easily  works 


MATERIALS  AND  CONSTRUCTION       377 

out  of  shape  under  stress  if  not  well  braced.  It 
has  particular  merits  for  wing  bars  and  other  parts 
of  a  structure  to  which  it  may  be  required  to  tack 
fabric,  because  tacks  do  not  split  it  readily.  Elm 
is  one  of  the  lightest  of  the  hardwoods,  being  of 
about  the  same  weight  as  Honduras  mahogany, 
but  in  its  strength  and  density  it  really  comes  into 
an  intermediate  position  between  the  hardwoods 
proper  and  the  softwoods. 

Hemlock  is  a  fairly  strong  and  exceptionally 
light  wood,  the  ratio  between  its  weight  and 
strength  being  such  as  to  rate  it  materially  higher 
as  a  structural  material  than  other  woods  popu- 
larly regarded  as  much  stronger. 

Hickory,  especially  second  growth  timber  rap- 
idly produced  in  the  form  of  new  shoots  from  the 
stumps  of  felled  trees,  is  one  of  the  strongest  and 
toughest  of  all  woods.  This  is  strictly  true  only 
of  the  so-called  "shellbark"and"white"  hickories. 
Water  hickory  is  rather  soft  and  comparatively 
light,  while  the  wood  of  the  pecan  (a  variety 
of  hickory)  is  hard  and  brittle,  but  nearly  all  of 
the  other  varieties  afford  the  highest  grades  of 
material  known  to  the  woodworker.  The  common 
uses  for  which  hickory  is  preferred  over  all  other 
woods  alone  speak  volumes  for  its  quality— axe 
and  pick  handles,  spokes  for  vehicle  wheels, 
vehicle  shafts,  oars,  etc.,  being  among  the  more 
familiar  applications.  In  flying-machine  construc- 
tion it  is  particularly  suitable  for  members  in 
which  it  is  desired  to  combine  great  strength  with- 
out the  bulk  necessary  in  spruce  and  other  soft 


378  VEHICLES  OF  THE  AIR 

wood  members  of  similar  resistance.  For  propel- 
lers it  is  probably  unequalled.  Hickory  particu- 
larly resists  splitting  and  transverse  fracture, 
breaking  when  it  does  break  gradually,  with  a 
tearing,  fibrous,  splintered  parting.  It  decays 
readily,  for  which  reason  structures  of  hickory 
must  be  well  protected  from  the  weather  by 
suitable  finishes. 

Holly  is  a  hardwood  of  fairly  light  weight  and 
superior  qualities,  and  is  particularly  resistant  to 
splitting,  but  the  difficulty  of  securing  it  in  suit- 
able sizes  and  qualities  restricts  its  use. 

Mahogany,  of  the  common  quality  from  Hon- 
duras, is  perhaps  the  lightest  of  all  the  true  hard- 
woods, and  in  thin  veneers,  with  crossed  grain, 
has  great  strength,  though  ordinarily  it  is  regarded 
as  more  remarkable  for  the  quality  of  finish  it 
will  take  than  it  is  for  purely  structural  merits. 
Spanish  mahogany,  though  somewhat  stronger,  is 
considerably  heavier. 

Maple,  though  not  the  strongest  of  hardwoods, 
is  lighter  than  most,  does  not  split  easily,  and  is 
superior  to  most  other  timbers  in  its  ability  to 
retain  fine  edges  and  corners  under  exposure 
to  conditions  that  tend  to  cause  chipping  and 
marring. 

Oak,  though  widely  recognized  as  one  of  the 
strongest  of  woods,  is  too  heavy  to  measure  up  well 
from  flying-machine  standpoints. 

Walnut,  though  rather  brittle,  is  very  strong 
and  light,  and  the  best  French  or  Circassian  wal- 
jiuts  are  very  successfully  used  in  the  manufacture 


MATERIALS  AND  CONSTRUCTION       379 

of  wooden  propellers,  though  they  seem  unsuited 
to  less-specialized  uses. 

SOFTWOODS 

The  distinguishing  quality  of  the  softwoods  is 
their  great  bulk  for  a  given  weight,  allowing  the 
highest  strength  to  be  secured  not  per  unit  of  bulk 
but  per  unit  of  weight. 

Pines,  of  a  great  range  of  varieties  and  quali- 
ties, are  among  the  strongest  of  all  timbers,  though 
the  different  kinds  vary  widely  in  their  properties. 
The  best  clear  white  and  red  pines,  free  from 
pitch,  are  second  only  to  spruce  in  their  lightness 
and  strength.  Both  of  these  are  extensively  used 
by  boat-builders,  besides  for  innumerable  purposes 
of  less  critical  requirements. 

Poplar — the  term  by  which  several  varieties  of 
whitewood  and  basswood  are  commonly  known — 
though  these  are  not  true  poplars  at  all — is  very 
tough  and  durable,  and  is  lighter  than  almost  any 
other  wood  possessing  strength  qualities  meriting 
consideration.  Its  weight  is  often  as  low  as 
twenty  pounds  to  the  cubic  foot— only  five  pounds 
heavier  than  cork — and  it  rarely  rises  as  high  as 
thirty,  even  in  specimens  selected  for  close  grain 
and  density. 

Spruce,  which  is  really  a  fir,  and  thus  closely 
related  to  the  pines,  is  a  wood  that  has  first  claim 
on  the  aeronautical  engineer's  attention.  This  is 
most  particularly  true  of  the  silver  fir,  and  the 
Norway  and  California  spruces,  all  of  which  are 
unequalled  for  the  spars  of  vessels,  while  the  sec- 


380  VEHICLES  OF  THE  AIR 

ond  is  widely  employed  by  musical-instrument 
makers  for  sounding  boards.  Selected,  clear,  and 
straight-grained  spruce,  or  "deal"  as  it  is  termed 
in  Europe,  rarely  weighs  over  thirty  pounds  to 
the  cubic  foot,  and  is  tremendously  strong  for  its 
weight.  Spruce  is  very  strong  and  stiff,  does  not 
easily  warp,  and  will  bend  as  much  as  elm  without 
breaking,  but  being  more  elastic  tends  more 
strongly  to  spring  back.  It  splits  very  easily,  for 


FIQUKB  178. — Sections  of  Wooden  Spars.  The  ends  sought  in  these  differ- 
ent constructions  are  light  weight,  great  strength,  and  a  minimum  resistance 
to  passage  through  the  air. 

which  reason  ends  should  be  well  wrapped  with 
wire  or  cord,  or  run  into  sockets,  while  holes  for 
nails,  screws,  and  bolts  should  be  bored  full  to 
avoid  any  wedging  effect. 

Willow,  the  "osier"  of  Europe,  is  the  con- 
stituent of  common  wicker  ware  and  furniture. 
Its  strength  in  proportion  to  weight  is  very  great 
because  of  its  extreme  lightness.  It  is  much  used 
for  balloon  baskets  (see  Page  105)  and  would  ap- 
pear to  have  a  field  before  it  in  way  of  seats  and 
housings  for  passengers  in  aerial  vehicles  (see 
Figure  248). 

VENEERS  AND  BENDINGS 

Veneered,  bent,  and  built-up  wooden  struc- 
tures are  usually  the  strongest,  because  of  the 
many  opportunities  they  present  of  eliminating 


MATERIALS  AND  CONSTRUCTION       381 

flaws,  of  crossing  grains  to  prevent  splitting,  and 
of  building  hollow  members  to  combine  the  maxi- 


FIGURE  179.  —  Built-Up  Hollow  Wooden  Spar. 

mum  of  strength  with  the  minimum  of  weight. 

Examples  of  built-up  wooden  structures  appear  in 

Figures  177,  178,  179, 
and  180.  The  hollow- 
box  wing  bars  of  the 
large  Langley  machine 


FIGURE  180.—  Built-up  Bamboo,  Hick-        (see    PaffC    137), 
ory,  and  Rawhide  Wing  Bar.  v  &         , 

bly  were  the  most 

elaborate  wooden  structures  ever  designed,  as  they 
were  certainly  among  the  lightest  and  strongest. 

METALS 

Though  weight  for  weight  very  few  of  the 
metals  are  stronger  than  the  best  woods,  and  these 
few  are  less  superior  than  is  commonly  supposed, 
within  a  given  volume  of  structure  no  materials 
approach  the  metals.  Particularly  in  their  tensile 
strengths  do  the  metals  excel  the  woods,  for  which 
reason  they  are  much  used  in  the  form  of  wire. 

For  stays,  strengthening  wrappings,  and  con- 
trol operation,  wire  is  probably  unrivalled.  An- 
other important  use  for  metal  is  in  sheet  form, 
which  also  is  cheap  and  inexpensive  to  handle, 
whether  used  for  adding  strength  to  joints  and 
angles,  or  for  more  elaborate  purposes.  Simple 


382  VEHICLES  OF  THE  AIR 

castings,  too,  of  the  lighter  aluminum  and  other 
alloys,  can  be  made  to  serve  many  useful  purposes. 

IRON 

Iron  as  a  structural  material  is  one  that  has 
suffered  from  comparison  of  its  impure  qualities 
with  ordinary  steels,  but  really  pure  iron  is  a  metal 
of  many  merits,  chief  among  which  is  a  resistance 
to  shock  loads  that  few  steels  equal,  while  in  sheer 
strength  it  is  at  least  superior  to  steels  of  common 
qualities  or  careless  manufacture. 

STEEL 

Ordinary  steel  is  a  compound  of  carbon  and 
iron,  with  the  carbon  ranging  from  10  to  200  ten 
thousandths,  -nmnr  being  known  in  the  steel  trade 
as  one  " point."  Thus,  "30-point"  carbon  steel 
is  steel  containing  T1JVW  of  carbon.  Steel  is  dis- 
tinguished from  all  other  materials  by  its  tre- 
mendous strength.  In  its  strongest  forms,  how- 
ever, it  is  hard  and  brittle,  for  which  reason  an- 
nealed varieties  of  moderate  strength  are  most 
used  in  structures  in  which  breakage  can  become 
very  serious.  Different  steels  weigh  from  480  to 
490  pounds  to  the  cubic  foot — from  3.5  to  3.7  cubic 
inches  to  the  pound.  The  strongest  form  of  car- 
bon steel  is  fine  wire,  such  as  piano  wire  and  the 
wire  used  in  bicycle  spokes.  The  latter  are  com- 
monly to  be  had  with  ultimate  tensile  strengths  as 
high  as  300,000  pounds  to  the  square  inch,  with  an 
"elastic  limit" — permissible  load  without  perma- 


bber-Faced  Silk  Used  on  "Golden  Flyer."  B. — Balloon  and  Aeroplane  Material. 


C. — Rubber-Faced  Silk  Used  on  "Silver  Dart."  D. — Treated   and  Untreated  Balloon  Silk. 


E. — Continental  Rubber-Faced  Percale  No.  109.       F. — Continental  Rubber  Faced  Percale  No.  111. 


G. — "Tanalite." 


H. — Continental   Unvulcanized   Joining   Material. 


L. — Balloon  or  Aeroplane  Fabric.  H. — Balloon  cr  Aeroplane  -.Fabric;  ^-T  ;  % 

FIGURE  184. — -Texture  of  Modern  Aeroplane  Fabrics — Reproduced  Actual  Size.  Of  the 
above,  A  weighs  only  3  ounces  to  the  square  yard  ;  C  weighs  only  2  ounces  to  the  square  yard  ; 
D  is  a  balloon  silk,  much  used  for  tents,  weighing  from  3  to  4  ounces  a  squard  yard  ;  E  and  F 
are  rubber-faced  percales  weighing  about  3y2  ounces  to  the  square  yard;  O  is  a  light  tent 
material  of  some  suitability  for  aeroplanes ;  H  is  for  covering  seams  ;  7,  J  and  K  are  light 
linen  fabrics,  and  L  and  M  are  suitable  for  either  aeroplanes  or  light  balloons.  The  strengths 
range  from  45  pounds  to  the  inch  of  width  in  C,  to  100  pounds  in  the  case  of  7,  J  and  K. 


MATERIALS  AND  CONSTRUCTION       383 

Bent  deformation — nearly  as  high  as  the  ultimate 
strength. 

Alloy  Steels  are  a  rather  modern  development 
in  steel  manufacture,  being  produced  by  the  addi- 
tion to  the  carbon  and  iron  of  small  quantities 
of  certain  less  common  metals — notably  nickel, 
chromium,  vanadium,  uranium,  and  tungsten.  By 
the  use  of  these  it  is  found  that  the  different  quali- 
ties of  ultimate  strength,  elastic  limit,  and  resist- 
ance to  shock  are  vastly  enhanced,  provided  that 
in  addition  to  the  proper  admixture  of  the  proper 
ingredients  the  metal  is  subjected  to  proper  heat 
treatment  in  its  manufacture. 

In  the  best  grades  of  chrome-nickel  steel  elastic 
limits  of  110,000  and  120,000  pounds  to  the  square 
inch  are  not  uncommon  in  unannealed  qualities  of 
metal,  so  far  from  brittle  that  with  sufficient  force 
they  can  be  bent  180  degrees  without  fracture, 
while  the  same  steels  hardened  often  test  fully 
twice  as  high. 

It  is  one  of  the  interesting  problems  of  modern 
metallurgy  and  engineering  to  discover  just  what 
may  be  the  greatest  strengths  possible  to  secure 
with  combinations  of  different  metals — in  which 
combinations  it  is  to  be  noted  that  there  appears 
to  be  little  likelihood  of  any  advantageous  elimi- 
nation of  iron  and  carbon. 

It  has  been  stated  on  good  authority  that 
Krupps,  of  Germany,  has  produced  test  bars  of  a 
secret  tungsten-containing  steel  with  which  tensile 
strengths  of  over  600,000  pounds  to  the  square  inch 
have  been  achieved.  No  such  steel  is  at  present 


384  VEHICLES  OF  THE  AIR 

on  the  market  in  commercial  shapes,  nor  are  the 
torsional  and  other  qualities  of  these  extraordinary 
fibrous  and  tough  steels  supposed  to  be  very  high. 
It  is  a  difficulty  in  the  utilization  of  all  steels 
that  much  of  their  strength  depends  upon  their 
proper  heat  treatment. 

CAST  IEON 

Cast  iron  is  iron  admixed  with  an  excess  of 
carbon  over  the  amount  permissible  in  steels. 
Aside  from  the  facility  of  working  it  by  casting  in 
molds,  cast  iron  possesses  certain  qualities  that 
render  it  peculiarly  suitable  for  gasoline-engine 
cylinders.  These  qualities  are  its  resistance  to 
high  temperature,  its  immunity  from  corrosion, 
and  its  capacity  to  take  and  retain  a  much 
smoother  finish  than  it  is  found  possible  to  secure 
in  steel  or  other  metals  used  for  the  same  purpose. 

ALUMINUM  ALLOYS 

Though  practically  worthless  in  its  pure  form 
for  such  purposes,  some  of  the  alloys  of  aluminum 
with  other  metals  stand  second  only  to  the  best 
steels  among  the  metals,  and  are  even  superior  to 
these  in  their  ease  of  manufacture  without  impair- 
ment of  their  more  valuable  characteristics. 

Aerial  Metal  is  an  alloy  of  aluminum  and  lith- 
ium, is  remarkably  strong,  and  in  some  qualities  is 
only  one  and  one-half  times  as  heavy  as  water. 

Aluman  is  an  alloy  of  88%  aluminum  with  10% 
zinc  and  2%  copper.  It  is  one  of  the  strongest  of 
the  aluminum  alloys  and  is  readily  forged  and 
milled,  but  its  weight  is  an  objection  to  it. 


MATERIALS  AND  CONSTRUCTION       385 

Argentalium  is  a  recently  patented  alloy  of 
aluminum  and  silver,  originated  in  Germany. 
Little  data  concerning  its  qualities  are  as  yet  avail- 
able, though  in  the  preferred  proportions  its  spe- 
cific gravity  is  known  to  be  about  2.9. 

Chromaluminum  is  another  German  alloy  of 
patented  formula,  containing  aluminum  with 
chromium  and  other  ingredients.  It  weighs  the 
same  as  argentalium  and  is  stronger  than  any 
other  known  aluminum  alloy,  with  the  pos- 
sible exception  of  the  very  highest  qualities  of 
magnalium. 

Magnalium  is  an  alloy  of  aluminum  and  mag- 
nesium, the  proportion  of  the  latter  varying  from 
2%  to  10%.  Its  weight  is  less  than  that  of  pure 
aluminum,  and  in  its  strongest  qualities — those 
containing  the  most  magnesium — it  has  been  ex- 
tensively applied  in  aeronautical  engineering.  It 
resists  corrosion  about  as  well  as  aluminum,  and 
is  readily  cast,  forged,  machined,  rolled,  and 
drawn,  with  little  difficulty  in  realizing  its  excel- 
lent qualities  in  the  final  manufactured  shapes. 

Nickel-Aluminum  is  rather  heavier  and  not  as 
strong  as  magnalium. 

Partinium,  or  Victoria- Aluminum,  is  a  more  or 
less  secret  aluminum  alloy  much  used  in  Europe 
for  automobile  crankcases  and  gearboxes.  It  con- 
tains very  small  proportions  of  copper  and  zinc, 
casts  well,  and  is  very  light. 

Wolframinium  is  an  alloy  of  aluminum  with 
tungsten,  with  traces  of  copper  and  zinc.  It  is  the 
subject  of  a  German  patent  and  is  extensively 


386 


VEHICLES  OF  TEE  AIR 


used  in  the  Zeppelin  dirigibles  (see  Page  87). 
Wolframinium  is  readily  worked  into  almost  any 
desired  form,  and  is  fully  as  strong  as  the  more 
practical  qualities  of  magnalium,  but  it  weighs 
more  than  the  generality  of  aluminum  alloys. 

BRASSES  AND  BRONZES 

Copper  with  zinc,  tin,  aluminum,  phosphorus, 
etc.,  constitutes  the  various  qualities  of  brasses 
and  bronzes,  which,  while  strong  and  easily 
worked,  tend  to  be  rather  too  heavy  for  most 
aeronautical  purposes. 

Aluminum  Bronze,  of  90%  copper  with  10% 
aluminum,  is  very  tough  and  elastic,  almost  incor- 
rodible, and  little  affected  by  changes  of  tempera- 
ture. It  casts  and  machines  well  with  proper 
methods,  but  is  very  heavy. 

Phosphor  Bronze  is  exceptionally  strong  in 
the  form  of  wire  and  small  fit- 
tings, such  as  turnbuckles  and 
the  like. 


METAL  PARTS 

Of  the  metal  parts  most  used 
in  modern  aerial  vehicles,  those 
of  greatest  importance  and  in- 
terest are  the  various  qualities  of 
wire,  strut  sockets,  turnbuckles, 
and  wire  tighteners.  Several  ap- 
proved methods  of  fastening  wire 
ends  are  illustrated  in  Figure 


FIGURE  181.  —  Meth- 
ods of  Fastening  Wire 
Ends.  If  tbe  loop  is 
made  like  the  upper 
view,  it  will  either 
come  loose  or  draw  into 
the  shape  that  is  shown 
In  the  lower  view, 
which  therefore  is  a 
proper  form  to  use  at 
the  beginning.  Another 
common  method  is  to  use 
the  flattened  piece  of 
steel  tubing  show*  at  a 
in  the  middle  view,  the 
wire  being  simply  bent 
as  at  ft  and  c,  which 
will  hold  it  securely. 


MATERIALS  AND  CONSTRUCTION       387 


FIGURE  182.— Strut  Sockets  and  Turnbuckles.  A,  B,  and  C  are  cast  alumi- 
num sockets  for  the  attachment  of  struts  to  the  sides  of  cross  members. 
D  is  such  a  socket  with  the  addition  of  a  lug  for  the  attachment  of  a  hinged 
member.  E  is  for  the  attachment  of  a  strut  to  the  end  of  a  cross  member. 
F  is  a  strut  tip,  for  hinging  to  a  socket  of  the  type  D.  G,  H,  I,  L,  and  M 
are  turnbuckles,  with  oppositely-threaded  ends,  for  tightening  wire  stays. 
These  are  operated  by  a  pin  thrust  through  the  center  holes,  and  are  locked 
by  running  a  wire  through  this  and  the  wire  eyes  in  the  ends.  K  is  a 
similar  turnbuckle,  but  is  kept  from  loosening  by  the  locknuts  at  its  ends.  J 
is  a  bolt,  eye-ended  for  the  attachment  of  a  wire  stay.  N  Is  a  clip  for 
clamping  wooden  bars  together,  and  O  is  a  wire  tightener,  similar  to  that 
in  Figure  183,  the  application  of  which  does  not  inrolve  cutting  the  wire. 

181,  while  in  Figure  182  are  shown  groups  of 
strut  sockets  and  turnbuckles,  and  in  Figure  183  a 
wire  tightener  that  avoids  cut- 
ting the  wire. 

CORDAGE  AND  TEXTILES 


FIGURE  183. — Wire 
Tightener. 


Cordage  is  of  great  utility 
from  many  standpoints,  and 
though  much  weaker  than  wire  for  a  given  size, 
with  some  materials  it  compares  most  favorably 
with  the  metals  on  the  basis  of  a  given  weight, 


388  VEHICLES  OF  THE  AIR 

while  its  great  flexibility  and  reliability  are  posi- 
tive advantages.  It  is  used  for  much  the  same 
purposes  as  wire. 

Fabrics  for  covering  wing  surfaces  probably 
possess  greater  all-around  advantages  than  any 
of  the  alternative  materials  that  are  occasionally 
proposed  or  tried,  and  like  the  other  materials  on 
which  the  aeronautical  constructor  must  rely  are 
easily  worked  up  and  comparatively  cheap,  in  even 
the  best  qualities. 

Cotton  cord,  though  very  strong,  is  less  used 
than  cotton  fabric,  which  is  the  commonest  mate- 
rial of  aeroplane  coverings,  of  which  a  variety  of 
typical  textures  is  illustrated  in  Figure  184. 

Linen  fabrics  have  been  discussed  on  Page  94. 

Silk  fabrics  also  have  been  considered  herein- 
before (see  Page  93). 

PAINTS  AND  VARNISHES 

Next  in  importance  to  the  production  of  a 
strong  and  efficient  structure  are  the  means  of 
maintaining  it  so.  These  particularly  involve 
avoidance  of  warping,  loosening,  and  rusting,  due 
to  the  action  of  moisture,  and  can  be  best  guarded 
against  by  the  proper  application  of  suitable 
finishes. 

Aluminum  Paint  is  used  over  all  wooden  sur- 
faces of  the  Wright  machines  for  a  double  pur- 
pose. One  is  the  protection  of  the  wood  and  the 
other  is  the  exposure  of  the  least  checking  or 


MATERIALS  AND  CONSTRUCTION       389 

cracking,  which  the  inelasticity  of  this  finish  makes 
at  once  apparent  in  the  form  of  fine  black  lines. 

Oils,  especially  boiled  linseed  oil,  exercise  a 
marked  preservative  effect  upon  woods  to  which 
they  are  applied.  It  is  a  question  though,  whether 
the  sometimes  recommended  soaking  of  wood  in 
oil  does  not  materially  weaken  it. 

Shellacs,  both  yellow  and  white,  because  of 
their  quick  and  smooth-drying  qualities,  are 
among  the  most  convenient  as  well  as  one  of  the 
best  of  finishing  materials. 

Spar  Varnish  is  particularly  to  be  recom- 
mended as  a  covering  for  glued  joints  and  other 
elements  upon  which  the  action  of  moisture  is  to 
be  feared. 

Miscellaneous  finishes,  other  than  the  fore- 
going, exist  in  great  variety.  Most  worthy  of 
present  consideration  are  the  various  enamels, 
japans,  and  lacquers  used  to  protect  metal  surfaces 
from  rust  and  corrosion. 

MISCELLANEOUS 

Of  other  materials  interesting  to  the  student 
of  practical  aeronautics  there  is  a  considerable 
number. 

Catgut,  from  the  intestines  of  small  animals, 
resembles  rawhide  in  its  quality  of  stretching 
when  wet  and  shrinking  as  it  dries,  making  it 
excellent  for  tightly-wrapped  bindings  of  spar 
ends.  It  is  much  used  in  musical  instruments  and 
for  stringing  snowshoes,  tennis  racquets,  etc. 


390  VEHICLES  OF  THE  AIR 

China  Grass,  used  for  chair  seats,  is  five-sixths 
as  strong  as  silk,  section  for  section,  and  is  little 
if  any  heavier. 

Hair,  especially  human  hair,  is  little  inferior  to 
silk  in  strength  and  lightness. 

Rawhide  is  much  used  for  covering  and  bind- 
ing together  the  parts  of  wooden  saddle  trees, 
being  applied  wet  and  allowed  to  shrink  on.  Thus 
used  it  would  appear  to  have  value  in  aerial- 
vehicle  elements,  as  is  suggested  in  Figure  180. 

Silk  Cord  is,  almost  without  exception  even 
among  the  metals,  one  of  the  strongest  structural 
materials  known,  as  is  evident  from  the  tabular 
comparisons  at  the  end  of  this  chapter. 

Silkworm  Gut,  the  so-called  " catgut"  of  fish- 
line  leaders,  is  very  close  to  silk  in  strength. 

ASSEMBLING  MATERIALS  AND  METHODS 

A  serious  obstacle  in  the  way  of  making  wood 
or  other  structures  of  great  strength  is  that  of 
devising  joints  of  strength  equal  to  that  of  the 
unbroken  material,  the  best  joints  tending  to  fall 
much  short  of  the  strength  that  it  is  easy  to  secure 
in  unbroken  members. 

Nails  for  fastening  together  wooden  parts  are, 
though  a  common  method,  a  most  inadequate  one 
for  anything  so  delicate  and  exacting  as  a  flying- 
machine  structure. 

Glues  and  Cements  afford  much  stronger  con- 
structions, especially  when  used  in  combination 
with  wrappings  of  wire,  cord,  leather,  or  rawhide, 
while  reinforcement  by  metal  plates  and  enlarged 


MATERIALS  AND  CONSTRUCTION       391 

ends  to  the  members  is  found  of  great  advantage 
in  wood  structures. 

Screws,  judiciously  used  to  prevent  the  slip- 
ping apart  of  different  elements  rather  than  as 
the  sole  means  of  securing  them  together,  are  not 
positively  objectionable,  though  it  is  desirable  to 
avoid  them. 

Bolts,  of  small  diameter  and  high-quality  steel, 
and  with  large  washers  under  heads  and  nuts,  are 
successfully  utilized  in  many  modern  aeroplanes, 
through  wood  and  metal  members  proportioned  to 
receive  the  bolt  holes  without  weakening. 

Clips,  of  the  type  illustrated  at  N,  Figure  182, 
are  excellent  for  clamping  two  or  more  wooden 
bars  together. 

Rivets,  while  not  the  best,  constitute  an  easily- 
applied  and  fairly  effective  means  of  joining  light 
metal  parts  together. 

Electric  Welding  is  an  almost  perfect  though 
not  always  readily  applicable  method  of  joining 
parts  of  similar  or  dissimilar  metals  with  mini- 
mum impairment  of  strength. 

Autogenous  Welding,  by  the  use  of  the  in- 
tense but  readily-localized  heat  of  the  oxy-acetyl- 
ene  flame,  is  an  excellent  modern  method  that  in 
expert  hands  is  easily  applied  to  a  great  variety 
of  assembling  operations. 

Brazing,  which  is  practically  a  means  of  solder- 
ing iron  and  steel  with  a  solder  of  very  soft  brass, 
or  "spelter",  was  first  developed  into  a  really  reli- 
able and  effective  process  in  the  evolution  of  the 
bicycle  industry.  Brazed  joints  appear  well  and 


392 


VEHICLES  OF  THE  AIR 


hold  well,  but  the  prolonged  heating  they  involve 
weakens  all  but  the  softest  annealed  steels. 

Soldering,  properly  done,  is  a  dependable 
means  of  securing  light  parts  together,  or  of  rein- 
forcing parts  primarily  held  by  other  means,  as  in 
the  case  of  twisted  wire  ends  (see  Figure  181), 
which  may  be  soldered  to  afford  added  security. 

TABULAE  COMPARISON  OF  MATERIALS 

WOODS 


NAME 

Pounds 
to  Cubic 
Foot 

Tensile 
Strength 
(in  pounds) 

Length 
of 
Material 
Sus- 
tained* 

Compressive 
Strength 
(in  pounds) 

Column 

Material 
Sus- 
tained* 

Alder  

6  000  —  7  000 



Ash      . 

43 
20 
43 
35 
64 

11  000—  

36,800 

4,600—  8,000 

26,760 

Beech  . 

8,000—12,000 
7,000  -10,000 
10,000-15.000 
12.000—14.000 
4,000-  9.500 

33,660 
41,000 
33,750 

8,000—  9,000 
5  000  —  10  000 

25,245 
41,000 
22,500 

Birch  

Boxwood  ••  .  . 

8,000-10.000 

Cedar  

35 

38,950 

4,000—  6,500 
5  000  —  6  500 

26,400 

Cherry  

Chestnut  
Elm  

*S6' 

*32' 
23 
43 

7,000—12.000 
8,000-13,000 
5.000-10,000 
5,000-12,500 

'53,000 

4,000—  4,800 
8,000  —10,000 

40,750 

Fir  (New  England  Spruce) 
Fir  (  Norway  Spruce)  
Hemlock  . 

56,250 

—  

10.000  -14,000 
10.000-15,000 

46,880 

8,000—  9,800 

32,800 

45 

8,000  —15,000 
6.000—10.000 
10,000-12,000 
10.000  -15,000 
5.000—  8,000 
8,000  —15.000 
8,000-10.000 
9,000  —12,000 
10.000-  
10,000-  
9,000-14,000 
7,000  -10,000 
8,000-10,000 
5,000  —  8,000 
3,000-  7,500 
5,000  —12,000 
7  000  -  10  000 

48,000 

3.000—  5.500 
8.000—  9,600 
7,500—  9,500 

;:;;;; 

Lignum  Vitae  

.... 



Mahogany  (  Honduras).  .  .  . 
Sahogany  (Spanish)  
aple  
Oak  (English) 

35 
45 
40 

32,800 

48.000 
36,000 

7,000—  8,000 
5,000—  6000 
6,500—10.000 
8  000  —10  000 

25,600 
21,600 

21,500 
26,800 

Oak  (Live). 

67 
43 

*29* 
34 

21,500 
33,500 

'37,240 
50,820 

Oak  (White)              

5,500—  8,000 
'7500—  ".*.'.'.".' 

Pine*  (Pitch)'.  .'  '.  '.  '.  '.*.  '.  '.  '.'.  '.  '.  '. 
Pine  (Red)  

Pine  (White) 

'6,000-'  7,506 
3,000—  6.000 
6,500  -10,000 

29,800 
42,350 

Pine  (Yellow)  

Plum  

Spruce  .................... 

'si* 

39 

7,000—  
5,000-10,000 

'46.450 

5,000—  8,000 
4  500  —  6  000 

27,870 

Teak  

10  000  —15  000 

6,000-10,000 
5,600—  7,000 



Walnut  (Black)       ..      .. 

8000-.... 

Walnut  (Hickory)  

42 

'37' 
50 

Walnut  (White)  
Willow  

io,ooo  —.'.'.'.'.' 

'28,800 

7,500—  9,000 
3,000—  6,000 

16,280 

Yew  

See  opposite  page. 


^5— >«: — 65 — — 65—- 


FIGURE  185. — Scale  Drawings  of  Wright  Biplane.      This   biplane   particularly   differs  from 
others  in  its  use  of  a  runner  alighting  gear  G  G,  starting  being  effected  by  auxiliary  devices,  inv 
ing  a  small  truck  on  which  the  machine  is  mounted,  a  wooden  rail  on  which  this  truck  runs,  an 
derrick  and  weight  arrangement  for  imparting  the  initial  impulse.     The  advantages  of  this  sys 
are  several.     Other  things  being  equal,  the  machine  is  lighter  than  those  in  which  wheeled  star 
gears  are  provided,  free  flight  is  attained  with  a  much  shorter  run,  and  the  runners  are  decid< 
superior  to  wheels  for  alighting  on  rough  ground,  over  which   they  slide  with  a  minimum  risk 
breakage.     The  main  planes  C  D  are  double  surfaced,  with  double  ribs  and  enclosed  wing  bars, 
are  narrowed  at  their  ends.     All  of  the  front  rectangles  are  rigidly  trussed  by  diagonal  wires 
also  are  the  center  rectangles  at  the  rear,  but  the  four  outer  rear  rectangles  are  kept  in  shape 
by  the  movable  guys  F  F  F  F,  which  pass  over  the  pulleys  E  E  E  E.  The  consequence  is  that  end 
movement  of  the  lower  of  these  wires,  effected  by  the    sidewise    movement    of    a    lever,    opposi 
warps  the  wing  tips  in  such  a  manner  as  to  control  lateral  balance  and  steering.     The  double 
tical  rudder  J,  carried  on  the  spars  KK,  is  worked  by  a  forward  and  backward  movement  of 
same  lever  that  when  laterally  moved  controls  the  wing  warping,  so  that  angular  movements  of 
lever  exert  a  compound  controlling  effect.     The  front    elevator    H   is    normally    flat    in    the    \i 
Wright  machines  but  when  moved  by  the  operating  bar  I  from  the  lever  N  it  does  not  merely  piv 
it  springs  into  curved  form,  with  the  concavity  upwards  or  downwards,  as  the  case  may  be,  so 
a  surface  of  maximum  effectiveness  is  presented  to  the  air.     This  construction,  which  is  the  sul 
of  a  patent,  is  shown  more  in  detail  in  Figure  84.     Propulsion  is  by  twin  propellers  A  B,  8J  fee 
diameter,  oppositely  rotated  by  the  ingenious  double-chain  driving  system  originated  by  the  Wrij 
in  which  one  chain — that  to  the  sprocket  Q — is  crossed,  while  the  other — to  0 — is  used  in  the  no: 
manner.     The  engine,  with  shaft  at  P,  is  a  25-horsepower,  four-cylinder,  water-cooled  design,  w< 
ing  about  180  pounds.     A  radiator  composed  of  vertically-placed    flat    copper    tubes    extending 
whole  distance  between  the  main  surfaces  takes  care  of  the  cooling.    Two  or  three  passengers  ca 
carried,  seated  near  the  center  of  the  lower  surface — just  enough  to  one  side  to  balance  the  we 
of  the  motor — with  their  feet  braced  against  the  bar  M.     For  convenience  in  storing  and  ship 
the  outer  ends  of  the  main  surfaces  dismount  at  E  E,  while  the  runners   disconnect  under  the  i 
of  the/ surf  #c^s.^    The  runners  in  the  latest    Wright  machines  are  made  considerably  hi 
formerly/  'Tiier  weights  of  the  different  Wright  machines  have  ranged  from  800  pounds  to 
'  pounds;  yaryrag  w^tb/tlie  design  and  the  weight  of  fuel  and  passengers  carried.    All  dimensions 
rgfivtorm -inches)  and  it- is  to  be  noted  that  the  sectional  dimensions  of  the  principal  wooden  men 
are  included.    For  further  details  of  the  Wright  construction,  reference  should  be  had  to  Figure 
75,  110,  139,  161,  163,  165,  166,  186,  187,  188,  189,  190,  191,  192,  193,  194,  195,  and  196. 


T 

i 

n 


H 


U , 


MATERIALS  AND  CONSTRUCTION       393 


METALS 


NAME. 

Pounds 
to  Cubic 
Foot 

Tensile 
Strength 
(in  pounds) 

Length 
of 
Material 
Sus- 
tained 

Compressive 
Strength 
(in  pounds) 

Column 
of 
Material 
Sus- 
tain*»d* 

Aerial  Metal 

98 
184 
168 
481 
184 
526 
444 

480 
482 
152 
184 
178 
485 
483 
490 
490 

60060-70.000 
42660—  

106.105 
33.380 
32.910 
27.460 
50  080 

Aluman  .. 



38393—  



92,430-  
63990—.... 

—  



85,320—86,742 
20,000-35,000 
56.880-58.302 
58,000—  
119448—  

23.750 
11.350 

17.400 
35650 



75.000-150.000 
28000* 

48,640 
'8.400* 

Copper  

Iron  (Pure  Wrought)  

41.238—63.990 
515  gfco— 

54,040 
44  560 

21.330—  

z  

99.540-132.246 

246,006  312  840 

16,020 

40,566 
91,940 

23,750 
6.560 

Steel  (Cast)  

80.000—  
22.000-  

Steel  (malleable  castings) 
Steel  (common  piano  wire) 
Steel  (tinned  piano  wire) 

—  

MISCELLANEOUS   MATERIALS 


16800—... 



39,520—  

_ 

25.000—36.175 

22752—... 

Glue  

500  —     750 
6.825-17.000 
9000—  



90 

75000—  

Horn  

Human  Hair  

.... 

ie'ooo'—  '.'.! 

50.000-79.000 





Leather           

3.000-  5,000 



Manila  



Rawhide  
filk.....  

'ioi 

12.000-  
35.000—62.028 

*7  "600—'.'.'.'.'.'. 

15,000-  
88,436—  .. 





ilkworaGut  
Whalebone  

42.240  -90.00C 





*This  lucid  method  of  making  weight-for-weight  Instead  of  bulk-for-bulk 
comparisons  of  strength  is  borrowed  from  R.  H.  Thurston's  "Materials  of 
Aeronautic  Engineering",  a  paper  that  was  presented  before  the  International 
Conference  on  Aerial  Navigation,  held  at  Chicago  in  1893,  and  which  contains 
much  information  and  data  hardly  excelled  in  completeness  and  accuracy  in 
any  more  up-to-date  publication. 


TRANSVERSE  STRENGTH  OF  WOOD  BARSf 


MATERIAL 

SIZE 

WEIGHT 

LOAD 

SUSTAINED 

Elm  

{x  1  z  12  inches 

51  ounces 

900  pounds 

x  1  x  12  inches 

4  1  ounces 

900  pounds 

1m      

li\  x  1A  x  12  inches 

880  pounds 

fpruce              

JiV  x  lit  x  12  inches 

xl     x  12  inches 

Spruce    . 

1     xl     x  12  inches 

|  Elm  

}f  x  1J  x  12  inches 

3i  ounces 

t  Soruce 

Eim  :.'.'.'..............:.'. 

}  x  2  x  12  inches 

J  Elm  

1*5  x  ii  x  12  inches 

J  Spruce  

A  x  il  x  12  inches 

2  ounces 

175  pounds 

tThese  tests  were  all  made  with  the  bars  supported  at  their  extreme 
ends.     $  Supported  edgewise. 


CHAPTER  TWELVE 

TYPICAL  AEROPLANES 

The  information  and  data  contained  in  this 
chapter  are  intended  to  provide  the  practical 
worker  with  such  particulars  and  details  of  suc- 
cessful modern  aeroplanes  as  will  enable  him 
readily  to  reproduce  and  operate  at  least  the 
simpler  machines,  several  of  which  are  exceedingly 
easy  and  inexpensive  to  build — a  fact  that  is  as 
absolutely  true  as  it  is  generally  unappreciated. 

No  attempt  has  been  made,  either  in  the  text 
or  in  the  scale  drawings  that  pertain  to  this  chap- 
ter, to  supply  slavishly  accurate  data  concerning 
every  trifling  detail  of  the  machines  considered. 
On  the  contrary,  there  have  been  deliberately  in- 
troduced a  number  of  carefully-considered  changes 
in  wholly  minor  details,  intended  to  reduce  the 
labor  and  cost  of  construction  in  directions  that 
otherwise  might  prove  sources  of  difficulty  to  the 
amateur  experimenter. 

It  seems  proper  here  to  emphasize  the  fact  that 
neither  the  construction  nor  operation  of  the  best 
modern  aeroplanes  call  for  the  extraordinary 
knowledge  and  expertness  they  are  popularly  sup- 
posed to  demand.  On  the  contrary,  rather  than 
much  knowledge  the  construction  of  an  aeroplane 

394 


FIGURE  186.— Side  View  of  Wright  Machine. 


FIGURE   187. — Three-Quarters  View  of  Wright  Machine. 


TYPICAL  AEROPLANES  395 

requires  much  care — the  most  painstaking  atten- 
tion to  the  perfection  of  every  last  detail.  As  for 
the  matter  of  operation,  with  many  of  the  most 
successful  machines  this  is  absolutely  easier  than 
learning  to  ride  a  bicycle  in  so  far  as  mere  manual 
skill  is  concerned,  though  the  need  of  a  cool  head 
and  reasonable  daring  is  not  to  be  escaped. 

By  far  the  most  essential  points  in  aeroplane 
building  are  provision  of  the  correct  wing  curva- 
tures and  the  proper  proportioning,  arrangement, 
and  control  of  the  different  sustaining,  stabilizing, 
and  balancing  surfaces — with  due  attention,  of 
course,  to  structural  strength  and  security.  The 
latter,  however,  may  be  quite  safely  left  to  any- 
one possessed  of  reasonable  mechanical  ability  to 
carry  out  largely  in  accordance  with  individual 
ideas  and  facilities,  which  with  the  exercise  of  rea- 
sonable judgment  are  as  likely  to  prove  practical 
and  satisfactory  in  one  case  as  in  another. 

The  initial  practise  flights  with  a  new  or  un- 
familiar machine  should  never  under  any  circum- 
stances be  undertaken  in  the  slightest  wind,  or 
elsewhere  than  over  an  unobstructed  and  very  uni- 
form surface  of  great  extent,  permitting  close-to- 
the-ground  flight  while  avoiding  the  dangers  of 
running  into  terrestrial  obstacles. 

It  should  be  clearly  understood,  too,  to  the  ex- 
tent that  the  reader  may  undertake  the  building 
and  operation  of  such  constructions  as  may  be  pro- 
tected by  patents,  that  the  law  only  permits  this 
when  such  reproduction  is  done  not  merely  for 
exclusively  personal  use  (which  many  persons 


396  VEHICLES  OF  THE  AIR 

imagine  is  allowed)  but  solely  and  only  for  the 
purpose  of  effecting  improvement. 

ANTOINETTE  MONOPLANES 

These  highly  successful  machines,  which  in 
their  latest  forms  have  evolved  to  the  construction 
illustrated  in  Figure  212,  which  shows  the  dimen- 
sions and  outlines  of  the  "  Antoinette  VII",  with 
which  Hubert  Latham  made  his  second  attempt  to 
cross  the  English  Channel,  are  much  too  compli- 
cated for  the  amateur  to  build,  as  must  be  very 
evident  from  the  details  of  the  Antoinette  wing 
structures  shown  in  Figures  71,  72,  and  101. 

BLEEIOT  MONOPLANES 

These  remarkable  machines  are  at  present  built 
in  three  principal  models,  of  which  the  single  pas- 
senger, the  "Bleriot  XI",  is  much  the  most  inter- 
esting, it  being  simple  and  inexpensive  to  build, 
light  in  weight  and  very  portable,  and  a  wonder- 
fully safe  and  speedy  flier,  as  is  sufficiently  attested 
in  the  records  it  holds.  In  reproducing  this 
machine,  it  will  be  sufficient  to  follow  substantially 
the  details  given  in  Figure  197.  The  exact  curva- 
tures of  the  wing  sections  are  not  to  be  had  in 
quite  exact  figures,  but  the  curves  shown  in  this 
scale  drawing  are  close  enough  approximations  to 
afford  satisfactory  operation  when  enlarged  to  the 
actual  size.  Most  of  the  smaller  parts  of  the  mono- 
plane— the  clips  for  assembling  the  framing,  the 
turnbuckles,  the  wheels  and  tires,  the  motors,  and 
the  aluminum-alloy  frame  braces  and  strut  sockets 


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398 


VEHICLES  OF  THE  AIR 


are  to  be  purchased  at  very  reasonable  prices  in 
Europe.  In  addition  to  following  Figure  197,  for 
a  clear  idea  of  minor  parts  a  study  should  be  made 
of  Figures  1,  73,  112,  118,  157,  164,  171,  199,  200, 
201,  245,  246,  247,  and  249.  The  weight  should  be 
kept  down  to  about  440  pounds  for  the  bare 
machine,  and  must  not  exceed  700  pounds  with 
fuel  and  passenger.  The  weight  of  the  22  horse- 
power Anzani  motor  with  which  one  of  these  ma- 
chines was  flown  across  the  English  Channel  was 
144  pounds,  that  of  the  wheeled  alighting  gear  was 
65  pounds,  and  of  the  frame,  or  fuselage,  about  60 
pounds. 

CHANUTE  GLIDERS 

These   gliders,   with   which   such   remarkable 
work    was    done    at    Dune    Park,    Indiana,    in 


Figure  237. — Chanute  Biplane  Glider. 


TYPICAL  AEROPLANES  399 

1895,  were  built  in  a  considerable  variety  of 
forms,  that  from  which  the  Wright  biplane  was 
developed  being  illustrated  in  Figure  237,  while 
the  essential  details  of  an  improved  construction 
are  shown  in  Figure  261.  Though  very  cheap  to 
build  and  quite  safe  and  practical  for  very  cau- 
tious experimenting,  these  early  gliders  fail  to 
embody  so  many  superior  features  used  in  present 
machines  that  it  seems  hardly  advisable  for  the 
amateur  of  today  to  consider  them  otherwise  than 
of  purely  historical  interest. 

CODY  BIPLANE 

This  biplane,  which  weighs  2,000  pounds  and  is 
the  largest  that  has  ever  flown,  is  patterned  rather 
closely  after  the  lines  of  the  Wright  machines,  the 
chief  differences  being  the  greater  size  and  the 
peculiar  system  of  controlling  lateral  balance  by 
manipulating  the  forward  elevator  elements  as 
ailerons.  Interesting  and  for  the  most  part  excel- 
lent features  of  design  are  the  arching  of  both  of 
the  main  surfaces,  the  flattening  of  the  main 
sustaining  surfaces  towards  their  ends,  and  the 
extensive  use  of  bamboo  members,  wrapped 
between  joints  to  prevent  splitting. 

Various  systems  of  arranging  the  main  surfaces 
have  been  experimented  with,  by  simply  changing 
the  lengths  of  the  vertical  spars  and  adjusting  the 
trussing.  The  latest  and  most  successful  is  that 
suggested  by  the  dotted  lines  in  the  front  view, 
Figure  202,  in  which  it  is  seen  that  the  9-foot  sepa- 
ration of  the  surfaces  at  their  centers  is  decreased 


400  VEHICLES  OF  THE  AIR 

to  8  feet  at  their  ends,  with  the  lower  surface 
arched  about  6  inches  and  the  upper  18  inches. 

Further  details  regarding  the  structural  details 
of  this  machine  will  be  found  in  Figure  202. 

CURTISS  BIPLANE 

The  main  structure  of  this  machine  is  a  central 
body  portion  EEK,  Figure  228  (also  see  Figure 
229),  mounted  upon  three  20x2^-inch  pneumatic- 
tired  wheels,  and  built  of  bamboo  and  Oregon 
spruce. 

The  main  surfaces  are  slightly  curved,  as  shown 
at  S,  and  the  chord  measurement  of  the  surfaces  is 
41/2  feet,  with  a  span  of  29  feet.  There  are  24 
light  laminated  spruce  ribs  in  each  main  surface, 
and  the  fabric,  rubber-faced  silk,  is  wrapped 
around  the  front  crossbars  of  the  wing  frames  and 
kept  taut  at  their  rear  edges  by  wire  edgings 
drawn  tight  over  each  rib  end.  The  silk  is  applied 
in  laced-on  panels — a  6-foot  center  section  and  four 
5-foot  sections  to  each  surface,  with  18-inch 
extensions  at  the  ends  of  the  wings. 

The  horizontal  rudder  I,  with  two  surfaces, 
each  2x6  feet  and  spaced  2  feet  apart  by  five  struts 
along  each  edge,  is  placed  10  feet  in  front  of  the 
main  surfaces,  while  a  single  horizontal  surface  of 
the  same  size  is  carried  10  feet  to  the  rear  to  serve 
as  a  steadying  tail.  The  vertical  rudder  is 
21^x2%  feet.  The  triangular  steadying  surface  x, 
at  the  center  of  this  rudder,  is  no  longer  used. 

Lateral  balance  is  provided  by  the  two  ailerons 
MM,  each  2x6  feet,  located  half-way  between  the 


FIGURE  189. — Paul  Tissandier  Seated  in  Wright  Biplane. 


FIGURE  190. — Count  de  Lambert  in  Wright  Biplane 


FIGURE    191.— Wilbur   Wright    Instructing   a    Pupil. 


402  VEHICLES  OF  THE  AIR 

ends  of  the  main  planes  and  with  their  centers 
aligned  with  the  two  end  pairs  of  main-surface 
struts,  so  that  these  balancing  planes  extend  far- 
ther to  the  sides  than  any  other  parts  of  the 
machine. 

As  the  machine  stands  on  the  ground  the  angle 
of  incidence  of  the  chords  is  about  6°.  This  is  but 
little  reduced  when  the  machine  is  in  flight. 

The  main  surfaces  are  separated  4%  feet  by 
six  spruce  struts  along  each  edge,  one  for  every 
four  spaces  between  ribs  except  at  the  center  and 
ends,  the  latter  overhanging  the  end  struts  18 
inches  and  the  center  space  having  five  rib-open- 
ings between  struts.  All  rectangles  thus  formed 
are  rigidly  braced  by  stranded  diagonal  wires. 
From  the  top  and  bottom  of  each  of  the  four  struts 
at  the  corners  of  the  center  section,  two  similar 
12-foot  bamboo  members  are  carried  forward  and 
rearward  to  junctions  with  the  sides  of  the  front 
and  rear  elevators,  which  are  pivoted  at  these  junc- 
tion points.  The  ends  of  the  front  elevator  are  of 
crossed  steel  tubes,  with  the  pivotal  points  well 
forward,  under  the  center  of  pressure. 

From  about  the  centers  of  the  rear  pair  of  extra 
struts  in  the  middle  of  the  main  surfaces,  two  of 
the  heaviest  spruce  members  (about  1^x2  inches) 
used  in  the  machine  extend  downwardly  and  for- 
wardly  to  a  junction  with  the  axle  ends  of  the  front 
wheel  of  the  running  gear — about  5  feet  in  front 
of  the  front  edge  of  the  main  surfaces.  These 
members  are  attached  to  the  front  pair  of  extra 
struts,  immediately  in  front  of  which  the  seat  is 


FIGURE  192. — Details  of  Wright  Biplane  Strut  Connections.  Note  the  manner  in  which 
the  struts  c  are  fastened  in  U-shaped  metal  sockets  at  the  center  of  the  machine  and  hooked 
to  the  wing  bars  a  in  the  flexible  wing  ends.  The  plate  d  indicates  the  point  at  which  the 
wings  unship  for  convenience  in  shipping  and  storing,  while  6  b  are  the  double  rib  members. 


FIGURE  193. — The  Wright  Runner  Construction.  The  solid  ribs  //*  serve  to  support  the 
motor,  operator,  etc.  The  other  ribs  6b  are  so  built  up  as  to  enclose  the  wing  bars  aa  between 
the  double  surfacing  of  fabric.  The  attachment  of  the  forward  curved  members  of  the  runners 
at  f  is  clearly  apparent  upon  close  examination. 


FIGURE  194. — Side  View  of  Wright  Runner  Construction.     The  reference  lettering  is  the 
same  as  in  the  preceding. 


*     I  :>  * 


TYPICAL  AEROPLANES  403 

placed  for  the  operator,  with  a  foot  rest  in  front 
of  the  seat. 

The  front  wheel  of  the  running  gear  is  carried 
in  an  ordinary  bicycle  fork,  and  is  additionally 
braced  by  a  vertical  member  from  this  fork  to 
cross  members  between  the  four  bamboo  braces  of 
the  front-elevator  support.  These  two  cross  mem- 
bers are  in  turn  braced  by  vertical  side  bars 
between  their  ends,  tying  together  each  side  pair 
of  bamboo  elevator  braces.  Two  struts  also  run, 
one  from  each  side  of  the  front  wheel,  forward  to 
a  cross  tie  about  18  inches  from  the  juncture  of 
each  side  pair  of  elevator  braces. 

The  rear  wiieels  of  the  running  gear  are  located 
under  the  rear  center  pair  of  main  frame  struts, 
in  bicycle  forks,  and  are  stayed  laterally  and  fore- 
and-aft  chiefly  by  framing  of  light  steel  tubes. 
From  the  center  of  this  steel  frame  a  wooden  bar 
runs  forward  to  the  front  wheel.  Light  wooden 
runners,  to  protect  the  lower  wing  ends  in  landing, 
are  placed  under  the  end  pairs  of  struts.  All  parts 
of  the  framing  are  liberally  wire-braced. 

Control  of  height  is  by  a  bamboo  steering  pillar 
running  from  the  steering  wheel  to  the  center  front 
strut  of  the  front  elevator,  this  strut  rising  above 
the  upper  elevator  surface  to  hold  the  front  edge 
of  the  triangular  steadying  surface,  previously 
mentioned.  Pushing  or  pulling  on  the  steering 
wheel  causes  the  machine  to  descend  or  ascend. 
Turning  the  steering  wheel  operates  the  vertical 
rear  rudder  through  a  wire  cable  running  in  a 
groove  in  the  rim  of  the  wheel.  The  balancing 


404  VEHICLES  OF  THE  AIR 

planes  are  worked  by  swinging  the  body  sidewise 
in  a  steel  crotch,  the  side  of  the  planes  lifted  being 
the  side  swung  away  from. 

A  spoon  brake  applied  by  a  bamboo  plunger  to 
the  tire  of  the  front  wheel  permits  quick  stopping 
after  alighting  and  holds  the  machine  for  the  start. 

FABMAN  BIPLANE 

This  biplane — shown  in  Figures  81,  143,  207, 
and  208 — in  a  general  way  copies  the  earlier  Voisin 
constructions  (see  Figures  174, 204,  and  205),  from 
which  it  was  developed  by  the  addition  of  the 
hinged  ailerons  a  a.  a,  Figure  142,  the  removal  of 
the  vertical  panel  surfaces,  and  the  combination 
of  runners  with  the  wheeled  alighting  gear. 

LANGLEY  MACHINE 

In  the  opinion  of  many  who  should  know,  the 
large  Langley  double  monoplane,  which  plunged 
in  the  Potomac  because  of  defects  in  its  starting 
gear  after  similar  models  had  proved  thoroughly 
operative,  is  quite  capable  of  flying  in  calm 
weather — with  probably  some  doubt  as  to  its 
ability  to  land  otherwise  than  on  water  without  a 
smashup.  Its  details  were  simply  elaborations  of 
those  shown  in  Figure  70,  but  its  reconstruction 
in  the  present  era  of  better  proved  fliers  could 
possess  only  technical,  rather  than  practical 
interest. 

LILIENTHAL'S  MACHINES 

These  machines,  like  those  of  Chanute,  Lang- 
ley,  Pilcher,  and  Maxim,  are  now  properly  to  be 


FIGURE   195. — Rudder   Frame   of   Wright   Machine. 


FIGURE   196. — Elevator  Frame  of  Wright  Machine. 


TYPICAL  AEROPLANES 


405 


FIGURE  230.— Early  Lilienthal 
Monoplane  Glider. 


regarded  as  successful  only  from  the  standpoint  of 
past  rather  than  of  present  achievement,  so, 
though  they  flew,  and  under  certain  conditions 
flew  moderately  well, 
they  cannot  be  said  to 
possess  any  features 
that  would  warrant  fur- 
ther experiment  with 
them  The  earlier  Lilienthal  gliders  were  mono- 
planes, illustrated  in  Figures  230  and  231,  and 

with  details  given  in 
Figure  263,  but  the 
final  construction  was 
the  biplane  sketched  in 
Figure  232.  This  can- 
not be  said  to  have 
proved  any  great  merit 
up  to  the  time  of  the  accident  that  resulted  from  it, 
though  it  was  the  final  form  to  which  Lilienthal 
had  evolved  his  ideas. 


FIGURE  231. — Lilienthal  Monoplane 
Glider. 


FIGURE  232. — Lilienthal's  Biplane. 
MAXIM  MULTIPLANE 


This  great  machine,  the  heaviest  ever  built, 
proved  quite  capable  of  lifting  its  weight,  but  there 
is  little  reason  now  to  suppose,  in  the  light  of  more 


406 


VEHICLES  OF  THE  AIR 


FIGURH  235. — Maxim  Multiplane.  Weight  8,000  pounds.  Propelled  by 
363-horsepower  steam  engine.  Span  126  feet,  area  4,000  square  feet,  cost 
$200,000. 

recent  knowledge,  that  it  could  without  radical 
modification  have  accomplished  controlled  and 
continued  flight.  Its  general  appearance  is  very 
well  suggested  in  Figures  235  and  236. 


FIGURE  236. — Maxim  Multiplane.  When  run  on  rails  at  Baldwyn's  Park, 
England,  July  31,  1894,  at  36  miles  an  hour,  this  machine  lifted  so  much 
more  than  its  weight  that  it  broke  a  set  of  rails  provided  to  hold  it  down 
and  thus  demolished  itself. 

MONTGOMEEY  MACHINE 

This  glider  is  of  such  absolutely  proved  capa- 
bilities, and  is  designed  upon  such  sound  prin- 


FIGURE  197. — Scale  Drawings  of  Bleriot  Monoplane  Number  XI.  Besides 
being  one  of  the  most  successful  of  present-day  fliers,  this  machine  is  a  com- 
paratively simple  and  inexpensive  one  to  build.  The  main  element  is  the  fusellage, 
or  frame,  A,  which  is  simply  built  of"  four  main  members  of  of  poplar,  separated 
by  transverse  bars  spaced  at  regular  intervals,  and  the  whole  rigidly  trussed  by 
diagonal  wires  h  crossing  all  rectangles.  This  frame  is  of  largest  size  at  the 
front  and  in  its  vertical  aspect  tapers  to  a  thin  edge  at  the  rear,  but  in  its  side 
aspect  the  taper  is  not  so  great.  The  wings  D  D  are  double  surfaced,  with  the 
wing  bars  inside  the  double  ribs,  and  the  ends  are  rounded — more  from  the 
rear  than  from  the  front.  They  are  demountably  attached  to  the  sides  of  the 
body,  which  in  its  forward  portion  is  covered  with  fabric  but  at  the  rear  is  left 
open.  The  front  edges  of  the  wings  are  rigidly  stayed  by  flat  steel  tapes  wwww 
and  x xx x  (not  wires)  to  the  overhead  framing  H  and  to  the  chassis.  The  rear 
edges  can  be  differentially  warped  by  pulling  on  the  wires  tttt,  which  are 
attached  to  the  pedestal  G  and  operated  by  the  wheel  N.  The  rear  rudder  F 
effects  horizontal  steering,  and  is  controlled  by  the  pedal  P.  Vertical  steering 
is  by  the  rocking  tips  K  K  of  the  rear  surface  E.  The  starting  and  alighting 
gear  consists  primarily  of  the  two  fixed  wheels  B  B,  which  swing  on  the  links  a  a, 
against  the  rods  C  C.  They  are  strained  down  by  elastic  springs,  which  absorb 
the  shock  in  landing,  but  their  downward  movement  is  limited  by  leather  straps. 
It  is  to  be  noted,  in  the  construction  of  the  chassis,  that  the  front  of  the  frame  A 
rests  upon  the  two  rods  N  N,  which  are  crossed  at  top  and  bottom,  respectively, 
by  the  bars  e  ??i,  these  bars  carrying  at  their  ends  the  vertical  wooden  columns  on 
which  the  sleeves  at  the  tops  of  b  b  slide.  The  single  rear  caster  wheel  is  mounted 
to  absorb  shock  by  the  action  of  a  device  closely  resembling  that  employed  for 
the  frpntf<w5ieQls.  Propulsion  is  by  the  single  wooden  tractor  screw  J,  6|  feet  in 
di&tfefeft'  jand  mounted  directly  on  the  engine  shaft.  The  engine  shown  is  the 
three-^cylinder,  V-shaped,  air-cooled  Anzani,  of  22-25  horsepower,  with  which  the 
Aressto^^o^-tfee'  English  Channel  was  accomplished,  but  many  other  motors  have 
been  successfully  used  on  the  same  machines.  The  pilot's  seat  at  M  is  com- 
fortably located  in  a  small  cockpit,  as  shown.  In  the  side  view,  the  machine  is 
shown  in  its  flying  attitude,  its  ground  attitude  being  indicated  by  the  dotted 
lines.  The  machine  operates  very  successfully  as  a  road  vehicle  with  the  wings 
dismounted  and  tied  against  the  sides  of  the  frame,  steering  being  them  effected 
by  the  rudder  F,  the  surfaces  E  K  K  keeping  the  rear  end  off  the  ground.  Dimen- 
sions are  given  in  feet  and  fractions  of  feet. 


X 


%fi 


-*«t 


'&-&&A 

f^iy. 

F 


% 

r'     i  : 
^    j! 
—  ---!•' 


Nj. 


;e 

^^^  ^XT^.%XV  ^.xxx^L^^^TOv  ' 

^^^^^  j 


5.:*-v;:s  ; 

•j-0*   :»  .,.*• 


TYPICAL  AEROPLANES  407 

ciples,  that  with  substantial  construction  and 
proper  precautions  it  is  probably  one  of  the  safest 
of  all  machines  with  which  to  practise  flying.  The 
drawing  and  details  given  in  Figure  225  do  not 
conform  in  certain  minor  measurements,  propor- 
tions, and  details  to  the  machines  used  in  the  Cali- 
fornia flights,  but  have  been  compiled  from  a  copy 
rather  hurriedly  built  by  the  writer  for  personal 
experiment.  They  are  close  enough,  however,  to 
the  description  of  Montgomery's  own  machines, 
as  illustrated  in  Figures  226  and  227  and  in  the 
patent  drawings  in  Figure  260,  to  supply  a  basis 
from  which  the  cautious  student  will  be  able  to 
secure  remarkably  successful  flights  if  he  will 
develop  the  apparatus  and  his  own  abilities  in  a 
conservative  manner,  preferably  by  practise  over 
water.  This  machine  being  a  patented  device,  no 
one  can  reproduce  or  use  it  unless  prepared  at 
any  time  to  prove  that  such  reproduction  or  use  is 
solely  for  experimental  purposes,  with  a  view  to 
improvement. 

PILCHEE  GLIDEES 

Judged  by  most  of  the 
results  obtained,  espe- 
cially When  flown  Mtewise  FIGUKB  233.— PHcher  Glider.  The 
,        ,         .         ,,              ,     .,          .  "Hawk." 

by  towing  through  the  air 

at  the  end  of  a  cord,  the  later  Pilcher  gliders, 
sketched  in  Figures  233  and  234,  were  very  safe  in 
calm  weather.  Even  the  tragedy  that  resulted  in 
the  death  of  their  designer  was  definitely  due  to 
a  breakage,  rather  than  to  any  fault  fairly  ascrib- 
able  to  the  principle  of  the  machines,  though  they 


408  VEHICLES  OF  THE  AIR 

lacked  the  stabilizing  and  balancing  elements  of 
current  constructions. 

K.  E.  P.  MONOPLANES 

These  machines,  which  have  sustained  more 
weight  per  unit  of  area  than  any  other  built,  and 
on  occasion  have  proved  excellent  fliers,  are  still 

the  subjects  of  frequent 
modification  and  much  ex- 
perimenting by  their  de- 

FIQUBE  234.— Pilcher  Glider.   The     Signer,      Robert      Esnault- 

Pelterie,  besides  which 

they  are  rather  difficult  to  build.  For  these  reasons 
no  drawings  are  given  of  their  construction,  but 
the  views  in  Figures  119,  222,  223,  and  252  have 
been  selected  with  the  special  purpose  of  convey- 
ing a  clear  idea  of  their  essential  details. 

SANTOS-DUMONT  MONOPLANE 

This  wonderful  little  machine,  of  well-proved 
flying  capabilities,  is  perhaps  more  to  be  com- 
mended than  any  other  to  the  attention  of  those 
who  may  wish  to  reach  results  at  the  least  possible 
expense  and  with  a  minimum  of  experimenting. 
Moreover,  Santos-Dumont  has  unselfishly  refused 
to  patent  any  of  the  details  on  which  he  might  have 
secured  protection,  frankly  desiring  that  the 
widest  possible  use  be  made  of  his  work.  In  addi- 
tion to  the  working  drawing  and  details  in  Figure 
221,  Figures  102,  116,  141,  217,  218,  219,  220,  and 
238  should  be  studied  as  examples  of  Santos- 
Dumont  's  experimental  and  final  constructions. 


FIGURE  198. — Bleriot  Monoplane  Number  XII. 


.FIGURE   199. — Bleriot  Monoplane   Number  XI. 


FIGURE   200. — Front  View  of  Bleriot  XI. 


FIGURE   201. — Three-Quarters  View   of   Bleriot  XI. 


TYPICAL  AEROPLANES  409 

VOISIN  BIPLANE 

The  Voisin  biplanes  are  almost  as  simple  and 
stable  as  the  box  kites  that  they  so  closely  re- 
semble, besides  which  it  is  probably  the  case  that 
they  constitute  the  least  patented  and  the  least 
patentable  of  all  constructions.  For  this  reason 
anyone  who  may  choose  to  work  from  the  draw- 
ings and  details  given  in  Figures  206,  and  172,  204, 
and  205  can  do  so  with  the  assurance  of  reaching 
a  successful  result  with  a  minimum  conflict  with 
patent  rights, 

WEIGHT  BIPLANE 

This  widely  known  machine  was  for  a  consider- 
able time  by  far  the  most  successful  of  all  power- 
driven  aeroplanes,  especially  in  the  hands  of  a 
thorough  expert  in  its  use,  besides  which  it  is 
quite  simple  and  inexpensive  to  reproduce.  The 
Wrights,  however,  very  positively  assert  the 
broadest  possible  claims  on  its  construction,  and 
at  present  evince  a  disposition  to  prevent  the  com- 
mercial exploitation  of  all  machines  not  of  their 
design  or  manufacture.  The  essential  details  of 
the  most  modern  type  of  Wright  biplane  are,  how- 
ever, given  in  Figures  110,  134,  161,  163,  165,  and 
166,  and  in  Figures  185  to  196,  inclusive,  it  being 
supposed  that  the  reader  will  use  his  own  judg- 
ment about  avoiding  possible  infringement.  The 
exact  wing  curves  of  the  Wright  machines  have 
not  been  published,  but  it  is  known  that  in  success- 
ful models  they  are  parabolic,  with  the  chord  very 
long  in  proportion  to  the  focal  length. 


CHAPTER  THIRTEEN 

ACCESSORIES 

In  considering  the  development  of  aeronautical 
mechanisms,  it  is  evident  that  besides  the  flying 
mechanism  proper  there  is  inevitably  involved  an 
increasing  number  of  one  kind  and  another  of 
accessory  devices,  most  of  which  will  have  to  be 
especially  devised  or  adapted  for  the  new  needs. 

Many  of  these  accessories  in  themselves  present 
problems  demanding  the  best  efforts  of  the  ablest 
investigators.  For  example,  the  necessity  for  the 
strongest  possible  lights,  to  penetrate  great  dis- 
tances into  foggy  atmospheres,  the  need  for  de- 
vices for  keeping  track  of  speeds  and  distances 
traveled,  and  particularly  to  aid  in  the  mainte- 
nance of  straight  courses  against  tendencies  to  lat- 
eral drift,  are  most  apparent.  In  addition  to  these 
there  is  the  more  perfectly  met  requirement  of 
means  for  indicating  altitudes,  temperatures,  etc. 

LIGHTING  SYSTEMS 

Naturally,  in  casting  about  for  means  of  illumi- 
nation and  light  projection  suitable  for  application 
to  aerial  vehicles,  the  most  valuable  suggestions  are 
in  a  majority  of  cases  to  be  derived  from  the 
automobile. 

Thus  it  is  found  that  the  various  types  of  acetyl- 

410 


FIGURE  238. — Santos-Dumont's  "Demoiselle"  in  Flight. 


FIGURE  239. — Paulhan's  Voisin  in  the  Douai  to  Arras  Flight.     This  flight,  over  a  distance 
of  12y2  miles,  was  performed  on  July  19,  1909,  in  23  minutes. 


ACCESSORIES  411 

ene  lighting  systems — oil  lamps,  electric  lamps, 
etc.,  found  suitable  for  automobile  use — can  be 
more  or  less  readily  applied  to  the  newer  purpose, 
the  chief  difficulty  in  the  way  of  making  such  appli- 
cation entirely  satisfactory  being  the  necessity  for 
even  greater  light-giving  power  with  an  absolutely- 
minimized  weight. 

ELECTRIC  LIGHTING 

Electric  lighting  so  far  has  not  been  extensively 
applied  to  automobile  illumination,  though  it  is 
rapidly  increasing  in  vogue. 

This  appears  to  be  mainly  because  the  storage 
battery  is  too  decidedly  heavy  as  a  source  of  suf- 
ficient amounts  of  current — a  difficulty  that  in  its 
present  development  condemns  it  utterly  for  appli- 
cation to  aeronautical  vehicles — while  the  difficulty 
of  running  a  dynamo  from  a  connection  with  the 
variable-speed  engine  that  must  be  used  for  pro- 
pelling the  car,  without  at  the  same  time  getting 
into  most  serious  problems  in  the  direction  of  cur- 
rent regulation,  is  the  other  of  the  two  great  diffi- 
culties that  beset  the  application  of  electric  lighting 
to  automobiles. 

Advantages  of  Uniform  Motor  Speed,  such  as 
seems  invariably  to  be  required  in  the  use  of  any 
aeronautical  engine,  go  a  long  way  to  relieve  the 
electric  dynamo  from  the  shortcomings  and  dis- 
abilities that  it  is  found  to  possess  in  attempted 
applications  to  automobile  lighting. 

Arc  Lamps  constitute  the  most  concentrated 
and  efficient  of  all  devices  for  utilizing  electric  cur- 


412  VEHICLES  OF  THE  AIR 

rent  to  produce  light,  though  they  hardly  can  be 
considered  the  most  convenient,  since  for  their  suc- 
cessful operation  the  maintenance  of  the  arc  in  the 
focus  of  a  paraboloid  mirror  must  be  secured  either 
by  frequent  hand-adjustment  or  by  complicated 
automatic  adjustment. 

Incandescent  Lamps  are  far  and  away  the  most 
convenient,  simple,  and  reliable  of  all  forms  of 
electric  illumination,  and  in  the  modern  metallic- 
filament  lamps — the  tantalum  and  particularly  the 
tungsten- — are  remarkably  efficient,  some  modern 
tungsten  lamps,  consuming  little  more  than  one 
watt  of  current  to  the  candlepower.  By  the  expe- 
dient of  closely-coiling  the  filaments,  the  light 
source  in  an  incandescent  lamp  can  be  very  closely 
located  in  the  focus  of  the  mirror  or  lens,  thus 
securing  a  more  concentrated  and  powerful  beam 
with  less  actual  candlepower  than  is  required  with 
most  other  types  of  lamps.  Another  advantage,  in 
providing  against  burned-out  lamps,  is  that  re- 
placements are  very  light  to  carry  and  are  readily 
placed  in  the  sockets. 

An  objection  to  the  tungsten  lamp  in  ordinary 
uses  is  the  fragility  of  the  filament,  especially  in 
lamps  of  high  candlepower  worked  on  high  voltages 
— involving  very  long  and  fine  filaments.  Tungsten 
lamps  for  automobile  service,  however,  have  been 
made  very  substantial  simply  by  virtue  of  the 
shortness  and  thickness  of  the  filaments  suitable 
for  operating  with  the  low  candlepowers  and  from 
the  low  voltages  commonly  used.  With  the  dynamo 
as  a  source  of  current,  as  seems  the  likely  develop- 


FIGURE  202. — Scale  Drawings  of  Cody  Biplane.  This  machine,  though  an  excellent  flier,  is  so 
and  cumbersome  that  its  reproduction  is  hardly  a  task  for  the  amateur — unless  a  reduced  co 
undertaken.  In  its  general  details,  this  biplane  is  very  closely  patterned  after  the  Wright  ma< 


bl 

I).-. 


with  numerous  differences  in  minor  particulars.  The  main  planes  A  A  are  double  surfacec  iver 
built-up  ribs  that  enclose  the  wing  bars  in  such  manner  as  to  avoid  the  possible  resistances  that  )  j  be 
set  up  when  these  are  exposed.  In  trussing  up  the  wings,  the  best  results  are  secured  with  j  pro- 
nounced droop  or  arching  of  the  surfaces,  as  is  suggested  by  the  dotted  lines  in  the  front  view  This 
arching  is  greater  for  the  upper  surface  than  for  the  lower.  The  end  ribs  are  of  flatter  culture 
than  those  nearer  the  center,  much  as  in  the  Montgomery  glider,  and  to  this  feature  doubtless  ii  |>  be 
attributed  the  speedy  flight  of  which  this  biplane  is  capable,  in  spite  of  its  combination  of  gr<  !  size 
with  not  extraordinarily  high  power.  Lateral  balance  is  maintained  very  peculiarly — by  dif  jiilar 
manipulation  of  the  rocking  elevator  surfaces  B  B,  which  when  worked  together  serve  merely  1  steer 
up  or  down,  but  which  otherwise  tilt  the  machine  to  right  or  left.  In  addition  to  this  means  of  f  Itrol, 
wing  warping  has  been  successfully  applied,  as  also  has  been  the  use  of  ailerons.  In  fact,  ftb  hree 
means  have  been  experimented  with,  both  independently  and  in  various  combinations.  The  opera  n  of 
BB  is  by  the  control  rods  K  K  which  move  in  unison  with  a  forward  or  rearward  swinging^  the 
steering  pillar  and  oppositely  when  the  wheel  F  is  rotated.  The  vertical  surface  0  is  simply  as  ady- 
ing  surface,  but  the  single  rear  rudder  «7  is  pedal  controlled  and  serves  to  counteract  the  lag 
outer  side  of  the  machine  in  turning.  Propulsion  is  by  twin  propellers  E  E,  oppositely  revolv 
crossed-chain  driving  system  practically  identical  with  that  used  by  the  Wrights.  The  cha 
specially  built  by  an  English  chain  manufacturer  to  provide  the  lateral  flexibility  desirable  for 
ing  the  best  results  with  crossed  drive.  The  starting  and  alighting  gear  consists  of  a  threes- 
chassis  DDE  and  the  springy  wooden  skid  /.  Wing  wheels  CC  are  used  at  the  ends  of  th 
main  .surfaces  to  protect  them  from  damage  in  case  of  sidewise  tilting  in  landing.  Liberal 
baroboa/is  njprde  in  the  construction  of  the  machine,  but  all  bamboo  spars  are  tightly  wrapped  w 
or  wire  between17  Joints  to  prevent  splitting.  The  weight  of  the  finished  machine,  with  fuel  ar 
5srK>T7&c  a/£qrfl>.'.  'Tiie  seat  for  the  pilot  is  directly  behind  the  control  wheel,  with  that  for  a  pj 
somewhat  higher  and  further  to  the  rear.  While  it  is  not  to  be  recommended  that  the  average 
menter  copy  this  particular  aeroplane,  there  is  no  doubt  but  what  its  construction  embodies  mi 
tures  of  interest  and  value  that  might  well  be  applied  in  smaller  or  modified  machines.  Furt 
its  great  size  constitutes  a  striking  example  of  what  can  be  accomplished  in  this  direction, 
introducing  elements  of  uncertainly  or  of  undue  fragility.  Dimensions  are  given  in  feet  and  inc 


by  a 

are 

'ord- 

?eled 

ower 

of 

cord 


nger 
peri- 
fea- 


"TfT 
| 
I 


1 

'     •        • 


ACCESSORIES 


413 


ment  in  aeronautics,  higher  voltage  seems  certain 
to  be  desirable  from  most  standpoints — lightness, 
efficiency,  etc. — which  may  direct  the  use  of  tung- 
sten lamps  into  rather  fragile  types.  Against  this, 
though,  is  the  fact  that  in  any  type  of  flying  ma- 
chine there  is  no  such  jolting  as  exists  in  the  case 
of  the  automobile,  the  machine  riding  on  the  air 
with  almost  perfect  smoothness. 

The  Nernst  Lamp,  the  current  consumption  of 
which  is  about  1.5  watts  to  the  candlepower,  is 
a  sort  of  incandescent 
lamp  of  very  remark- 
able design,  in  which 
the  very  short  and  thick 
filament  is  composed  of 
oxids  of  some  of  the 
rare  metals  —  princi- 
pally zirconium  and 
yttrium — is  a  good  con- 
d  u  c  t  o  r  of  electricity 
only  when  heated,  and  is  so  refractory  that  it  does 
not  require  enclosure  in  a  vacuum  to  permit  its  use 
without  burning  out. 

ACETYLENE 

Acetylene  is  one  of  the  heaviest  and  richest  of 
all  the  hydrocarbon  gases,  making  it  exceptionally 
well  adapted  to  the  production  of  intensely-lumi- 
nous flames  with  only  small  gas  consumption. 
Acetylene  is  most  conveniently  produced  by  the 
action  of  water  upon  calcium-carbid,  the  reaction 
turning  the  calcium-carbid  into  quicklime — which 


FIGURE  240. — Suggested  Nernst 
Lamp.  The  glower  b,  at  the  focus 
of  the  paraboloid  mirror  c,  receives 
current  from  the  dynamo  g,  with  the 
usual  balancing  coil  in  the  circuit  at 
/.  The  heating  coil  e,  however,  is 
mounted  on  the  hand-manipulated 
arm  d,  so  that  it  is  shunted  into  the 
circuit  by  the  switch  a  when  it  is 
swung  up  in  proximity  to  6. 


414  VEHICLES  OF  THE  AIR 

is  slacked  by  the  action  of  the  water — while  the 
carbon  released  from  the  decomposition  of  the 
carbid  combines  with  the  hydrogen  released  by 
the  decomposition  of  the  water  to  produce  the 
acetylene. 

Storage  Tanks  for  transporting  acetylene  in 
manufactured  form,  dissolved  under  pressure  in 
acetone,  are  widely  used  for  automobile  lighting 
and  are  exceptionally  safe  and  convenient.  Such 
tanks  containing  thirty  cubic  feet  of  gas  are  com- 
monly made  cylindrical,  about  6  inches  in  diameter 
and  16  inches  long,  and  weigh  about  30  pounds. 
It  is  somewhat  remarkable  that  such  a  tank,  under 
the  ordinary  pressure  of  something  like  225 
pounds  to  the  square  inch,  and  first  filled  with 
asbestos  or  other  absorbent  material  and  enough 
liquid  acetone  to  fill  the  tank  full,  will  contain  con- 
siderably more  acetylene,  dissolved  in  the  acetone 
(like  carbonic-acid  gas  in  the  water  of  soda-foun- 
tain beverages),  than  can  be  placed  in  the  same 
tank  empty.  Also,  while  the  gas  compressed  into 
the  empty  tank  would  be  a  very  dangerous  explo- 
sive, its  storage  in  the  acetone  seems  to  make  it 
perfectly  safe,  it  automatically  evaporating  as 
required  for  use  only  as  the  pressure  is  released. 

Acetylene  Generators  have  the  advantage  over 
acetylene  storage  tanks  that  they  are  rather  lighter 
for  a  given  gas  production  than  a  tank  for  the 
storage  of  an  equivalent  amount  of  gas.  There  are 
two  fundamental  systems  of  acetylene  generation — 
one  involving  the  "carbid-feed"  generator,  and 
the  other  the  "water-feed,"  By  all  means  the 


Model   Voisin   Biplane — With   tractor   screw   and   no   front   elevator. 


FIGURE  204. — Three-Quarters  Rear  View  of  Voisin   Biplane. 


FIGURE  205. — Three-Quarters  Front  View  of  Voisin  Biplane. 


ACCESSORIES  415 

most  successful  type  of  automobile  generator  car- 
ries the  carbid  in  a  wire  basket  in  the  upper  part 
of  the  container,  with  water  above  the  basket  and 
considerable  receiving  space  below  it  for  the  recep- 
tion of  the  slacked  carbid  which  is  jarred  out  be- 
tween the  wires.  Such  generators  operate  best 
when  subjected  to  considerable  shaking,  making 
them  even  less  available  for  aeronautical  use  than 
for  automobile  use,  and  are  very  prone  to  heat  up, 
with  a  consequent  production  of  tarry  gas  and 
much  obstruction  of  piping  by  gummy  deposits  and 
condensed  moisture. 

Acetylene  Burners  require  provision  for  admix- 
ture of  the  acetylene  with  a  great  excess  of  air, 
since  otherwise  a  blue-flame  or  imperfect  combus- 
tion results,  but  given  sufficient  air  admixture  com- 
bustion is  attended  with  the  production  of  an 
intensely  luminous  flame  of  great  brilliancy,  and 
of  a  quality  more  nearly  approaching  sunlight 
than  any  other  artificial  illuminant.  The  most 
widely  used  acetylene  burners  are  of  double- jet 
types,  arranged  to  impinge  two  round  jets  upon 
each  other  at  right  angles — the  two  flattening  at 
the  point  of  juncture  into  a  wide,  flat  flame. 

Within  the  last  year  or  so  a  new  type  of  acet- 
ylene burner  has  come  into  use  in  which  only  a 
single  flat  opening  is  used,  in  a  general  way  rather 
similar  to  the  ordinary  straight  slit  in  common 
illuminating  gas-burners  but  provided  with  several 
openings  for  the  inspiration  and  admixture  of  the 
necessary  air  required,  without  the  complication 
and  objections  that  apply  to  the  common  type. 


416  VEHICLES  OF  THE  AIR 

OXYGEN  SYSTEMS 

One  of  the  oldest  forms  of  very-concentrated 
high-power  illumination  is  the  calcium  light,  in 
which  a  small  button  of  lime  is  heated  to  incan- 
descence by  the  exceedingly  hot  blue  flame  from 
an  oxy-hydrogen  blowpipe.  This  particular  form, 
which  is  still  much  used  for  stereopticon  projec- 
tion, especially  where  electricity  is  not  available, 
requires  to  be  modified  to  present  any  possibility  of 
use  from  aerial- vehicle  standpoints. 

With  Hydrogen  it  of  course  is  necessary  to 
carry  a  tank  of  hydrogen  gas  under  pressure,  as 
well  as  the  necessary  oxygen  stored  in  the  same 
manner. 

With  Gasoline,  however,  used  from  the  regular 
supply  for  the  engine,  only  an  oxygen  tank  being 
carried,  there  have  been  developed  quite  satisfac- 
tory automobile  headlights  in  which  a  jet  of  vapor- 
ized gasoline  is  burned  in  combination  with  a  jet 
of  oxygen,  the  regulation  calcium  button  being  used 
to  produce  the  white  and  powerful  light  by  its 
incandescence. 

With  Acetylene  and  oxygen  it  is  possible  to 
secure  a  blue  flame  stated  by  some  authorities  to 
be  even  hotter  than  the  oxy-hydrogen  flame,  and 
therefore  capable  of  producing  an  even  more  bril- 
liant light  in  combination  with  the  lime. 

INCANDESCENT  MANTLES 

Incandescent  mantles  kept  hot  by  a  blue  flame 
from  a  more  or  less  modified  form  of  Bunsen 
burner  have  within  recent  years  become  one  of  the 


J¥0. 


K 


FIGURE  206.  —  Scale  Drawings  of  Farman's  Voisin.  The  main  planes 
A  A  of  this  machine,  which  is  of  the  characteristic  Voisin  construction,  are 
double  surfaced,  over  built-up  ribs  enclosing  the  wing  bars.  Lateral  equi- 
librium is  maintained  wholly  by  the  automatic  action  of  the  vertical  panels 
between  the  ends  of  the  main  surfaces  and  those  of  the  tail  J.  Horizontal 
steering  is  effected  by  the  vertical  rudder  K,  operated  by  turning  the  wheel 
H,  but  the  machine  can  turn  only  in  very  wide  curves.  Vertical  steering  is 
by  the  front  elevator,  the  two  elements  of  which,  F  F,  can  be  rocked  only  in 
unison  by  pushing  or  pulling  on  the  wheel  R,  which  connects  with  them 
through  the  hinged  joint  G,  M  is  simply  a  forwardly  extended  framework, 
or  prow,  to  carry  F  F  and  brace  the  alighting  gear  C  C  D  D.  This  alighting 
gear  consists  of  the  two  wheels  C  C  rigidly  mounted  in  the  framework  D  D, 
which  under  shock  rises  as  a  unit  against  the  springs  E  E.  Two  small  caster 
wheels  at  N  serve  to  support  the  tail  J,  which  is  merely  a  stabilizing  element. 
An  eight-cylinder,  water-cooled,  V-shaped  Antoinette  motor  of  50  horsepower 
furnished  the  power  in  the  particular  machine  described,  in  which  the  1\- 
foot  single  propeller  was  mounted  directly  upon  the  engine  crankshaft,  but 
many  different  engines  have  been  used  in  different  Voisin  machines,  and 
in  at  least  one  instance  flights  have  been  accomplished  with  a  geared-down 
propeller.  The  fuel  tank  is  shown  at  0,  the  radiator  at  P,  and  the  pilot's 
seat  at  I.  Weights  of  different  elements  of  a  recent  Voisin  machine  are  as 
follows  :  Main  surfaces,  180  pounds  ;  chassis,  250  pounds  ;  tail  framing,  40 
pounds;  tail  surfaces,  55  pounds;  tail  wheels,  13  pounds;  vertical  rudder, 
lOrrjounds;  .elevatorr  32T  pounds;  engine,  320  pounds;  radiator  and  water, 
8(3;po.vmds;r  pilot,  jlTO^prounds—-  a  total  of  1,150  pounds.  The  area  of  the 
majnrsiyrfapesrisr  445  square  feet;  of  the  elevator,  45  square  feet;  and  of 
'r 


feet.  All  dimensions  are  given  in  inches.  For 
further  details  of  the  Voisin  machines  reference  should  be  had  to  Figure 
88,  showing  the  frame  of  the  newest  biplane  of  this  make,  from  which  the 
forward  elevator  is  eliminated;  Figure  142,  showing  Farman's  modifica- 
tion of  the  Voisin  into  a  triplane;  Figure  168,  showing  a  machine  of  this 
type  rising  from  the  ground;  Figure  172,  picturing  the  Voisin  alighting 
gear;  Figure  203,  showing  the  most  recent  model  of  this  machine;  and 
Figures  204  and  205,  giving  characteristic  views  of  recent  Voisins. 


I        i 


\  \/ 


, 

'  ' 


• 


ACCESSORIES  417 

commonest  of  all  means  of  illuminating  buildings, 
streets,  etc.,  and  are  in  their  best  forms  very  effec- 
tive, durable,  and  of  sufficiently-concentrated  in- 
tensity to  permit  of  their  use  with  reflectors. 

Latterly  the  incandescent  mantle  has  been  very 
successfully  applied  to  the  illumination  of  railway 
carfc,  in  which  the  jarring  unquestionably  is  much 
greater  than  in  aerial  vehicles.  Mantles  for  this 
purpose  usually  are  made  very  small,  of  the  in- 
verted type,  and,  if  necessary,  as  hard  and  almost 
as  strong  as  porcelain. 

With  Gas,  ordinary  illuminating  gas  is  prefer- 
able for  ordinary  use,  chiefly  because  of  its  cheap- 
ness, but  in  railway  cars  the  richer  and  purer 
hydrocarbons  such  as  are  supplied  by  the  Pintsch 
system,  in  which  acetylene  is  used  in  combination 
with  other  gases,  are  found  most  satisfactory. 

With  Liquid  Fuels  incandescent  mantles  can  be 
operated  very  successfully,  the  best  fuels  being 
gasoline,  alcohol,  and  kerosene,  in  the  order  named. 

OIL  LAMPS 

That  oil  lamps  are  not  without  points  of  su- 
periority over  many  of  the  most  scientific  and 
highly-developed  methods  of  light  production  is 
rather  evident  from  the  fact  that  this  in  many 
ways  primitive  system,  for  such  important  services 
as  railway  switch  lamps,  signals,  cars,  lighthouses, 
etc.,  has  been  found  more  satisfactory  than  any- 
thing more  modern. 

Sperm  Oil,  with  or  without  modifying  admix- 
tures, possesses  certain  points  of  superiority  over 


418 


VEHICLES  OF  THE  AIR 


kerosene  and  other  petroleum  oils,  for  which  rea- 
son it  is  much  used  in  lighthouses,  signal  lamps, 
and  for  other  purposes  in  which  a  high  degree  of 
reliability  and  cleanliness  is  sought. 

Kerosene  is  superior  to  most  other  oils  in  its 
calorific  value  for  direct  combustion  by  the  use  of 
a  wick,  besides  which  it  is  universally  available. 

EEFLECTOKS 

Since  the  light  from  most  ordinary  sources  of 
illumination  is  more  or  less  evenly  cast  in  every 

direction,  its  projec- 
tion in  a  single  direc- 
tion, as  is  usually  re- 
quired  for  vehicle  use, 
and  as  must  be  espe- 
cially the  case  for 
aerial  vehicles,  re- 
quires the  use  of  a  re- 
fracting surface  de- 
signed to  collect  and 


/'• 


24i.—  Lens  Mirror,  show-   gather  all  the  radiating 

g     ow    he  light  from  the  focus  Is  111 

refracted  by  the  glass  and  reflected  rayS    aS    Completely    aS 
by  Its  mirror  backing  Into  a  beam  of 

parallel  rays.  pOSSlble  into  a  Compact 

beam  of  non-divergent  parallel  rays.  In  automo- 
bile lamps  the  so-called  "lens  mirrors"  are  chiefly 
used,  being  composed  of  glass  lenses,  parabolically 
curved  in  their  sections  and  their  rear  surfaces 
silvered  with  a  reflecting  coating.  Such  mirrors 
naturally  possess  an  immunity  from  tarnish,  par- 
ticularly with  open  flames,  that  is  not  possessed  by 
metal  reflectors.  A  typical  lens  mirror  is  shown  in 


I 


FIGUKE  209. — Side  View  of  Maurice  Farman's  Biplane.  This  machine  resembles  both  the 
Voisin  and  the  Farman  machines — the  former  in  its  running  gear  and  the  latter  in  the  absence 
of  the  vertical  panels. 


FIGURE  210. — Front  View  of  Maurice  Farman's  Biplane. 


FIGURE  211. — Farman's  Modified  Voisin.     Note  the  ailerons  at  a  a  a,  and  the  added  upper 
surface,  making  the  machine  a  triplane. 


.:  ;•  '•  ' 


ACCESSORIES 


419 


Figure  241.  Metallic 
reflectors,  however,  in 
deep  paraboloid  form,  of 
the  locomotive-reflector 
type,  intercept  and  re- 
flect in  a  desired  direc- 
tion a  greater  quantity 
of  the  light  than  any 
other  type,  especially 
if  a  plano-convex  lens, 
Figure  242,  is  placed  in 
front  of  the  flame  to 
gather  the  cone  of  rays 
that  would  pass  out  the 
end  of  the  paraboloid. 


FIGURE  242.  —  Locomotive  Head- 
light. All  light  rays  not  Intercepted 
and  thrown  forward  in  a  parallel 
beam  by  the  paraboloid  metal  re- 
flector are  refracted  by  the  plano- 
convex lens  in  front  of  the  light 
source,  the  portion  of  the  metal  re- 
flector behind  this  lens  being  made 
spherical  so  as  to  return  the  rays  it 
receives  back  through  the  focus  to 
the  lens. 


ARRANGEMENT  OF  LIGHTS 

With  all  land  and  water  vehicles,  standard  sys- 
tems of  lighting  arrangements  are  established  by 
custom  and  often  by  law.  For  example,  all  the 
world  over,  a  modern  automobile  carries  two  front 
headlights  (usually  acetylene),  often  in  conjunc- 
tion with  two  oil  or  other  side  lamps  showing  a 
beam  ahead  as  well  as  a  less  amount  of  light  at  the 
side,  and  a  single  red  tail  lamp.  A  single,  powerful 
searchlight  or  projector,  mounted  high  on  the  cen- 
ter of  the  dashboard,  is  often  added  for  rough 
cross-country  travel.  For  water  craft  the  most 
usual  requirement  is  that  of  a  red  light  showing 
forward  and  to  the  port  (left)  side  with  a  green 
light  forward  and  to  starboard  (right),  though 
various  arrangements  of  masthead  lights,  stern 


420  VEHICLES  OF  THE  AIR 

lights,  and  not  infrequently  powerful  searchlights 
shown  forward,  are  in  extensive  use. 

In  case  of  the  really  great  development  and 
multiplication  of  aerial  traffic  which  many  believe 
to  be  impending,  there  might  be  a  further  necessity 
for  distinguishing  between  the  lights  of  different 
air  craft  by  characteristic  arrangements  of  lights 
as  is  done  in  the  case  of  ocean  liners. 

SPEED  AND  DISTANCE  MEASUREMENTS 

One  of  the  greatest  problems  in  aerial  naviga- 
tion is  certain  to  be  the  correct  or  even  approxi- 
mately correct  estimation  of  speed  and  distance. 
To  begin  with  there  is  the  sufficient  difficulty  of 
constructing  any  highly-accurate  device  for  ex- 
actly registering  the  speed  at  which  the  air  passes 
a  given  point,  or,  what  amounts  to  the  same 
thing,  measuring  the  progress  of  any  given  point 
through  the  air.  But  in  addition  to  this  question 
there  is  the  much  greater  one  of  allowing  for  the 
drift  of  the  vehicle  with  the  whole  body  of  the 
atmosphere  across  the  surface  below — a  drift  that 
can  add  to  or  subtract  from  the  speed  of  the  ve- 
hicle over  the  earth's  surface,  or  that  can  produce 
leeway  drift  far  in  excess  of  the  most  ever  encoun- 
tered in  water  navigation. 

ANEMOMETERS 

Anemometers,  for  the  estimation  of  speeds 
through  the  air,  will  doubtless  closely  resemble  the 
very  valuable  and  satisfactory  devices  that  are 
widely  used  by  weather-bureau  and  meteorological 


FIGURE  207. — Side  View  of  Farman  Biplane.  This  machine,  which  holds  the  world's 
distance  and  duration  records,  is  particularly  interesting  because  of  the  use  of  the  wheels  g  in 
combination  with  the  runners  f  in  the  alighting  gear. 


HARDING 

_  .,--*-  -.--'----  -,., 


FIGURE  208. — View   of  Paulham's   Farman   Biplane,   which   made   the   London-Manchester 
cross-country  flight  of  180  miles. 


ACCESSORIES 


421 


stations  for  re- 
cording wind 
velocities.  The 
commonest  form  is 
the  four-arm  type 
illustrated  in  Fig- 
ure 243,  with  hemi- 
spherical cups  at 
the  end  of  each 
arm,  the  greater 
resistance  opposed 
b  y  the  concave 
sides  of  these  cups 
over  that  opposed 


by 


tlie     COnveX        PIGURH    243.— Anemometer    Speed    and    Dls- 

pmiQino*  VJ}T*i-  tance  Recorder.     The  cups,  by  the  greater  re- 

uauoiiig    vaxi  Distance    of    their    concave    over    their    convex 

TT>    4-~\nr\    a-r\tifiA  surfaces,    cause    the    vertical    shaft   to    revolve 

ILL    lllti    fepccU.  at  a  rate  proportionate  to  the  movement  through 

...  ,-,       ,  the  air.     The  speed  and  total  number  of  revo- 

rOtatlOn       tnat  lutions  are  shown  in  miles  per  hour  and  miles 
traveled,    by    the    automobile    speed    indicator 

Closely       »f"»-  and  tne  odometer  at  the  base  of  the  shaft. 


n 
01 

verv    cosey    ap- 

proximates  varia- 

tion in  the  movement  of  the  air  —  or  through  the 

air.    Another  common  form  of  anemometer  is  that 

in  which  a  small  windmill-like  fan  is  revolved  by 

the  passage  of  the  air  through  its  vanes.    This 

type  always  must  be  faced  to  the  wind. 

Either  of  the  types  of  anemometer  described 
can  be  connected  up  to  ordinary  speed-indicating 
or  revolution-counting  devices,  as  pictured  in 
Figure  243. 

MICELLANEOUS 

Another  possible  method  of  keeping  track  of 
distance  traveled  through  the  air  is  simply  by  a 


422  VEHICLES  OF  THE  AIR 

revolution  counter  or  a  speed  indicator,  or  both, 
driven  from  the  propeller  shaft.  An  aerial  pro- 
peller of  good  design  gives  a  very  uniform  slip 
from  its  theoretical  rate  of  pitch  progress  (see 
Pages  239  and  244),  for  which  reason  each  revo- 
lution of  the  propeller  means  a  quite  definite  dis- 
tance moved  through  the  air.  So,  with  a  sufficient 
amount  of  preliminary  experiment  to  determine 
the  average  amount  of  such  movement  with  a  given 
number  of  revolutions,  it  should  be  possible  to 
calibrate  a  speed  indicator  or  revolution  counter 
to  register  from  the  propeller  turns  a  closely  accu- 
rate indication  of  the  speed  and  the  amount  of 
travel.  Something  of  this  sort  is  very  commonly 
done  in  the  navigation  of  steam  vessels,  the  engi- 
neers of  which  invariably  place  greater  reliance 
on  the  record  of  propeller  revolutions  than  they 
do  upon  any  other  available  means  of  determining 
speed  or  distance. 

COMPASS 

The  magnetic  compass,  the  use  of  which  is  con- 
temporaneous with  almost  the  earliest  history  of 
navigation,  though  its  really  scientific  application 
is  more  due  to  the  modern  mariner,  will  undoubt- 
edly serve  a  purpose  in  the  aerial  craft  of  the 
future,  though  in  its  application  to  these  there  are 
not  to  be  overlooked  some  most  serious  difficulties. 

The  particular  shortcoming  of  the  compass  as 
a  useful  adjunct  to  aerial  navigation  is  that 
while  it  can  be  depended  upon  to  show  the  different 
directions  with  absolute  or  approximate  accuracy, 
it  affords  little  assurance  that  the  vehicle  is  really 


FIGURE  213. — Three-Quarters  View  of  Antoinette  III 


FIGURE   214. — Rear   View   of  Antoinette   V.     In   this  view   the   ailerons  a   a   and   the   bal- 
ancing rollers  6  7;  are  well  shown. 


FIGURE  235. — Front  View  of  Antoinette  VII. 


FIGURE  216. — Rear  View  of  Antoinette  VII.  This  is  the  machine  with  which  Latham 
flew  20  miles  in  his  second  attempt  to  cross  the  English  Channel.  Ailerons  are  discarded  in 
favor  of  rocking  the  whole  wing,  and  the  alighting  gear  is  reduced  to  the  wheels  g  g  g  and  «. 


ACCESSORIES  423 

progressing  in  any  given  direction,  even  though 
it  be  kept  headed  in  this  direction  and  continuously 
driven  at  full  speed.  This  is  because  in  addition 
to  the  actual  movement  through  the  air  there  also 
must  be  considered  the  movement  of  the  air  itself — 
a  movement  that  will  be  of  evident  effect  if  the 
ground  is  in  sight,  but  which  at  night  or  over  water 
can  hardly  disclose  itself  even  though  it  may  be 
causing  a  lateral  or  angular  drift,  or  even  a  direct 
movement  backwards,  at  greater  speed  than  the 
air  speed  of  the  vehicle.  At  the  time  this  is  writ- 
ten the  most  interesting  case  in  which  this  effect 
has  been  observed  occurred  in  Bleriot's  flight 
across  the  English  Channel,  in  the  course  of  which, 
during  a  very  few  minutes  when  the  land  on  both 
sides  was  out  of  sight  because  of  fog,  several  miles 
leeway  were  made  in  spite  of  a  supposed  proper 
direction  of  the  machine,  involving  subsequent 
coasting  along  the  English  shore  to  make  a  landing 
at  the  point  for  which  a  supposedly  straight  course 
had  been  steered  at  the  outset  (see  Figure  265). 

FIXED-DIAL    COMPASSES 

Compasses  in  which  the  dial  is  fixed,  with  the 
needle  moving  over  it,  are  commonly  used  for  sur- 
veying because  of  certain  points  of  convenience 
that  they  possess  for  this  purpose.  They  also  are 
used,  though  for  this  purpose  they  are  less  suit- 
able, by  explorers  and  others  in  going  over  land. 

FLOATING  DIAL  COMPASSES 

Compasses  in  which  the  dial  is  fastened  to  the 
needle,  which  is  attached  with  its  points  in  registry 


424  VEHICLES  OF  THE  AIR 

with  the  north  and  south  marks  on  the  dial,  and  the 
whole  so  mounted  as  to  turn  very  lightly — usually 
by  floating  in  a  liquid — constitute  the  Common  form 
of  mariner's  compass.  They  have  the  advantage 
of  pointing  not  only  the  north  and  south,  but  the 
other  cardinal  and  intermediate  directions  in  such 
a  way  that  any  given  direction  can  be  readily  seen 
at  a  glance,  without  revolving  the  case. 

BAKOMETEKS 

A  barometer  carried  on  an  aerial  vehicle  serves 
two  purposes,  that  of  indicating  altitude  and  that 
of  forecasting  weather  changes.  In  either  case 
the  barometer  is  simply  a  pressure  gage,  indicating 
the  atmospheric  pressure  at  any  given  time. 

MERCURIAL  BAROMETERS 

Perhaps  the  most  reliable  type  of  barometer  is 
that  in  which  the  air  pressure  is  balanced  against 
that  of  a  column  of  mercury,  the  weight  of  this 
liquid  being  so  great  that  a  thirty-inch  column  of 
it  is  sufficient  to  afford  a  pressure  of  14.7  pounds 
to  the  square  inch — balancing  the  entire  pressure 
of  the  atmosphere  on  the  given  area  at  sea  level. 

ANEROID  BAROMETERS 

In  aneroid  barometers  the  air  pressure  is  indi- 
cated by  the  action  of  the  pressure  against  the  thin 
metal  sides  of  one  or  more  flat  vacuum  chambers, 
of  thin,  elastic,  metal  disks,  between  which  springs 
are  placed  to  resist  the  pressure.  A  simple  multi- 
plying device  converts  the  very  slight  movement 


FIGURE  217. — Side   View  of  Santotf-Dumont's  Belt-Driven   Monoplane. 


FIGURE   218.— Front   View   of   Santos-Dumont's   Belt-Driven   Monoplane. 


FIGURE   219.— Side   View   of  Santos-Dumont's   "Demoiselle. 


FIGURE  220.— Front  View  of  Santos-Dumonf  s  "Demoiselle."     This  machine    which  weighs 
less  and  costs  less  than  many  motorcycles,  is  the  smallest  machine  that  has  suciessfully  flown 


ACCESSORIES  425 

of  the  vacuum-cell  walls  into  the  more  ample  move- 
ment of  a  hand  around  a  circular  dial. 

WIND  VANES 

The  mounting  of  a  small  wind  vane  on  an  aerial 
vehicle  is  useful  not  in  that  it  can  afford  any  indi- 
cation of  lateral  drift  of  the  whole  atmosphere,  but 
to  the  extent  that  it  will  show  leeway  made  from 
a  straight  course  through  the  effect  of  unsymmetri- 
cal  forward  resistances  such  as  can  arise  in  the 
manipulation  or  adjustment  of  balancing  and  steer- 
ing devices.  To  be  of  the  highest  utility  such  a 
wind  vane  should  indicate  not  only  lateral  but  also 
vertical  deviation,  for  which  reason  a  ball  or  gimbal 
mounting  would  seem  to  be  the  proper  thing. 

In  the  Wright  brothers'  experiments  they  often 
use  a  short  strip  of  tape  or  cloth,  perhaps  a  half- 
inch  wide  and  a  couple  of  feet  long,  tied  to  some 
forward  part  of  their  biplane  so  that  by  the  angle 
of  its  drifting  back  towards  the  operator  an  indi- 
cation is  had  of  the  performance  of  the  vehicle. 

MISCELLANEOUS  INSTRUMENTS 

In  addition  to  the  more  important  instruments 
already  enumerated  there  are  several  others  that 
might  conceivably  prove  useful  or  requisite. 

The  use  of  a  level  as  a  sort  of  grade  indicator 
to  show  angles  of  ascent  and  descent  must  be  of 
evident  utility.  Such  a  level  already  applied  in 
some  aeronautical  experiments  is  that  illustrated 
at  Figure  254,  in  which  the  body  is  a  light  metal 
cup,  covered  by  a  spherically  curved  glass  top  and 


426 


VEHICLES  OF  THE  AIR 


filled  with  alcohol  except  for  the  small  space  occu- 
pied by  the  bubble  at  the  top.  The  series  of  con- 
centric rings  or  grooves  in  the  inner  side  of  the 
glass  cover,  made  visible  by  filling  with  black 
enamel,  afford  instant  indication  of  longitudinal 

or  lateral  deviation  from  a 
normal  level  course  by  forc- 
ing the  bubble  away  from  its 
normal  position  at  the  center 
of  the  glass  to  a  position 
away  from  this  point  to  a 
distance  corresponding  with 
the  change  in  level  and  in  a 
direction  corresponding  with 
the  direction  of  the  change. 
A  quickly  manipulable 
sextant,  or  some  practical  or 
approximate  equivalent  of  this  valuable  instru- 
ment of  navigation,  seems  to  be  the  one  evi- 
dent hope — aside  from  methods  of  dead  reckoning 
— for  determining  and  maintaining  a  course 
against  a  lateral  drift  due  to  the  wind,  as  sug- 
gested on  Page  423.  The  difficulties,  however,  of 
making  reliable  observations  of  sun  or  stars  from 
aerial  vehicles  are  likely  to  prove  very  great. 

The  provision  of  a  timepiece  of  chronometer 
qualities  is  an  evident  necessity  if  long  aerial  voy- 
ages are  ever  to  be  undertaken.  As  is  well  under- 
stood by  all  in  the  least  degree  familiar  with  navi- 
gation, an  accurate  chronometer  is  the  modern 
navigator's  chief  reliance  for  determination  of  his 
longitude- 


FIGURE  224.  —  Universal 
Level.  This  consists  of  a 
metal  cup  with  a  curved  glass 
top,  beneath  which  a  bubble 
floats  in  a  liquid.  The  direc- 
tion of  its  movement  from 
the  center  shows  the  direc- 
tion of  its  tilting,  while  the 
amount  of  its  movement  over 
the  graduated  rings  on  the 
glass  is  a  measure  of  the  ex- 
tent of  the  tilting. 


FIGURE  245.— Side  View  of  Bleriot  XI  with  Wings  Tied  on  Frame. 


FIGURE  246.— Front  View  of  Bleriot  XI,   Showing  Demountable  Wings. 


FIGURE  247.— Assembling  Bleriot  XI. 


CHAPTER  FOURTEEN 

MISCELLANY 

In  addition  to  the  more  important  and  more 
evident  considerations  that  disclose  themselves  in 
any  survey  of  the  achievements  and  the  prospects 
of  modern  aerial  navigation,  there  is  discovered  a 
great  number  of  more  obscure  possibilities — possi- 
bilities at  the  present  time  impossible  to  appraise 
and  even  difficult  to  define,  but  nevertheless  con- 
stituting proper  subjects  for  some  measure  of 
attention. 

In  this  connection  it  is  perhaps  well  for  the 
reader  to  impress  upon  himself  the  idea  that  the 
aeroplanes  of  today,  despite  their  decidedly  re- 
markable recent  successes,  must  probably  bear  to 
the  more  nearly  perfected  mechanism  of  the  flying 
vehicle  of  the  not  distant  future  some  such  rela- 
tion as  was  sustained  by  the  automobile  of  ten  or 
fifteen  years  ago  to  the  wonderful,  practical,  popu- 
lar, economical,  and  in  every  essential  respect  suc- 
cessful vehicles  that  today  throng  the  streets  and 
roads  of  all  civilization,  and  around  the  construc- 
tion and  improvement  of  which  there  has  devel- 
oped a  science  that  in  itself  constitutes  a  special 
department  of  engineering  and  an  industry  in 
which  are  invested  hundreds  of  millions  of  dollars. 
It  may  seem  to  the  casual  reader  a  venturesome 

427 


428  VEHICLES  OF  THE  AIR 

thing  to  predict  any  similarly  extensive  develop- 
ment of  aerial  vehicles.  Yet  it  is  to  be  remem- 
bered that  even  the  most  accustomed  forms  of 
modern  transportation — the  railway,  the  steam 
vessel,  the  bicycle,  the  automobile,  etc.,  all  had 
their  very  inception  actually  or  almost  within  the 
lifetimes  of  people  now  living,  while  without  ex- 
ception their  development  from  the  experimental 
stage  to  the  status  of  unquestioned  utility  has 
covered  much  shorter  periods. 

Certainly  it  cannot  be  escaped  or  overlooked 
that  the  atmosphere  as  a  medium  of  travel  affords 
more  room  with  less  limitations  than  apply  to 
any  other  mode  of  transportation;  that  it  is  the 
medium  used  by  birds  for  the  transportation  of 
considerable  weights  at  great  speeds  with  absurdly 
small  power;  and  that,  though  the  bird  possesses 
the  almost  inimitable  coordination  of  animal 
mechanism,  man  has  nevertheless  proved  already 
capable  of  imitating  this  coordination  and  control 
not  only  in  a  considerable  degree,  but  also  with 
remarkable  success  and  safety — the  lives  so  far 
lost  in  this  growing  conquest  of  the  air  with 
heavier-than-air  machines  being  much  smaller  for 
given  distances  traveled  than  proved  the  case  in 
the  development  of  apparently  much  safer  means 
of  terrestrial  and  aquatic  travel. 

APPLICATIONS 

Concerning  the  possible  and  probable  applica- 
tions of  aerial  vehicles,  it  is  perhaps  easier  to  argue 
than  it  is  to  convince,  but  at  least  it  will  be  admit- 


FIGURE  221. — Scale  Drawings  of  Santos-Dumont  Monoplane.  This  is  the  lightest, 
least  expensive,  and  one  of  the  most  successful  power-driven  aeroplanes  yet  developed. 
The  main  frame  B  consists  of  three  bamboo  spars,  widely  spread  in  front  and  brought 
closely  together  at  the  rear.  One  of  these  spars  is  above  and  the  other  two  below, 
side  by  side.  All  three  of  these  spars  are  cut  at  L,  so  that  the  machine  can  be  readily 
taken  apart  and  reassembled  by  use  of  the  tubular  sleeves  placed  at  this  point.  Closely 
applied  wrappings  of  wire  or  cord  counteract  the  tendency  of  the  bamboo  to  split. 
The  monoplane  sustaining  wing  A  is  single  surfaced,  with  the  wing  bars  on  the  rare- 
faction side  of  the  ribs,  and  there  is  no  attempt  to  round  the  wing  tips  or  flatten  the 
curves  of  the  end  sections.  The  lateral  balance  is  maintained  by  wing  warping,  by 
the  wires  0  0,  which  pass  over  the  small  pulleys  shown  and  then  connect  directly  to  a 
laterally-movable  vertical  lever.  This  lever  is  ingeniously  operated  by  a  section  of 
tubing  sewn  into  the  back  of  the  operator's  coat  and  slipped  over  the  lever  when  he  is 
in  the  canvas  seat  E,  so  that  the  natural  swing  of  his  body  maintains  the  equilibrium. 
Fore-and-aft  balance  is  secured  by  movement  of  the  horizontal  rudder  surface  J 
through  the  control  wires  N  N  and  the  lever  C,  the  spring  Q  serving  to  maintain  the 
wires  taut  in  all  positions.  Lateral  steering  is  by  the  vertical  rudder  /,  operated 
by  the  wires  M  M  from  the  wheel  D.  Several  machines  of  substantially  this  same 
type  have  been  successfully  flown  with  different  engines,  both  air  and  water  cooled, 
but  all  of  somewhat  similar  two-cylinder,  horizontal-opposed  types.  The  most  satisfac- 
tory results  have  been  secured  with  the  Darracq  motor  pictured  in  Figure  116.  This 
engine  weighs  only  66rpcunds,  though  it  develops  35  horsepower,  and  is  water  cooled 
fryr  .the.  radiafyoi£  '.j£  ;?£,•  w&ich  consist  simply  of  a  large  number  of  parallel  tubes  ar- 
rang&d.'under 'the 'wing  surf  apes.  The  gasoline  tank  is  at  P.  The  wooden  propeller  H, 
6J  feet  ip»dietrwej$r,  Is  prpuntcd  directly  on  the  engine  shaft,  a  portion  of  the  advanc- 
/mg  'e$|eVcrfetlSe' sustaining  surface  A  being  cut  away  to  accommodate  it.  The  alight- 
ing gear  consists  simply  of  the  two  bicycle  wheels  F  F,  slanted  inwards  at  the  top  as 
shown  in  the  front  view,  and  supplemented  by  the  tubular  metal  skid  in  front  of  the 
rear  rudders.  The  weight  of  this  machine  is  about  240  pounds.  Dimensions  are  given 
in  feet  and  inches.  For  further  details  of  the  Santos-Dumont  machines,  of  the  par- 
ticular model  above  described  as  well  as  the  various  constructions  from  which  it  devel 
oped,  reference  should  be  had  to  Figures  116,  141,  217,  218,  219,  220,  and  238. 


r 


IB' 


20' 


•  .-.«:.'. 
••>•:  •.. 


MISCELLANY  429 

ted  that  such  vehicles  must  find  some  fields  of  use- 
fulness, whether  or  not  it  is  to  be  contended  that 
these  fields  will  prove  exceedingly  broad  or  excep- 
tionally limited. 

WABFARE 

War  being  fundamentally  an  affair  of  danger 
and  disaster,  all  possible  strictures  that  can  be 
leveled  against  the  safety  of  aerial  vehicles  must 
lose  force  when  confronted  with  this  application. 
Much  discussion  and  speculation  has  been  aroused 
by  the  contemplation  of  the  possibilities  of  the  fly- 
ing machine  in  war — even  books  having  been  writ- 
ten in  which  it  has  been  attempted  to  portray, 
often  in  the  most  interesting  manner,  phases  of  the 
warfare  of  the  future.* 

The  schemes  that  have  been  suggested  in  the 
way  of  tactics  and  methods  to  be  employed  in 
aerial  warfare  cover  the  widest  possible  range, 
from  the  ridiculous  to  the  plausible. 

A  somewhat  discussed  aspect  of  the  flying  ma- 
chine 's  war  possibilities  has  been  that  of  mounting 
on  dirigibles  and  other  aerial  craft  firearms  of 
types  similar  to  those  of  the  smaller  calibers  used 
in  land  and  naval  warfare.  Because  of  the  great 
weight  of  even  the  lightest  of  effective  modern 
weapons,  the  considerable  weights  of  ammunition 
required,  and  the  comparatively  low  accuracy  in 
firing  at  moving  targets  from  unstable  platforms, 
it  is  impossible  to  believe  that  any  real  success  can 
attend  such  plans.  Even  under  the  most  favorable 

*In  this  connection,  the  writer  has  particularly  in  mind  H.  G.  Wells' 
"War  in  the  Air." 


430  VEHICLES  OF  THE  AIR 

circumstances,  it  is  one  of  the  well-established  sta- 
tistics of  military  history  that  for  every  man  killed 
as  much  as  or  more  than  his  weight  in  metal  must 
be  shot  from  firearms.  It  therefore  seems  scarcely 
clear  how  aerial  vehicles,  necessarily  rather  lim- 
ited in  their  carrying  capacities — even  though 
great  further  progress  in  this  regard  be  made — can 
effect  very  material  damage  upon  the  unconcen- 
trated  troops  that  commonsense  modern  tactics 
have  already  dictated  as  a  means  of  minimizing 
danger  from  attacks  with  machine  guns  and  shrap- 
nel. Elimination  of  this  sort  of  aerial  warfare 
from  consideration  leaves  the  aerial  vehicle  with 
only  one,  but  a  sufficiently  dangerous  method  of 
attack — by  the  dropping  of  high  explosives  as  accu- 
rately as  may  prove  possible  into  the  weakest  and 
most  vulnerable  points  in  the  enemy's  military  and 
social  organization.  And  this  method,  as  specula- 
tion upon  it  is  indulged  in,  becomes  sufficiently 
horrifying  to  appall  the  most  skeptical  tactician  or 
hardened  soldier. 

Undoubtedly,  the  initial  points  of  attack  would 
be  on  the  sea  the  enormously  costly  mechanisms — 
the  battleships,  cruisers,  and  torpedo-boats — of 
modern  navies,  which  even  today  seem  open  to 
destruction  should  occasion  arise  by  very  ordinary 
application  of  the  capabilities  of  such  aeroplanes 
as  have  been  already  developed — working,  it  is  to 
be  emphasized,  not  individually  but  in  fleets,  with 
results  that  seem  quite  inescapable.  On  land  the 
points  of  attack  might  be  the  storehouses  of  mili- 
tary and  food  supplies,  or  even  the  property  in 


FIGURE  222.— Side  View  of  the  R.   E.   P.   Monopl 


FIGURE  224.— Captain  Ferber's  Dihedral    Biplane. 


.,%         •  .  '.  '  ''I  I  I 

*»     *   «'    •'    »      * 


MISCELLANY  431 

great  cities,  which,  all  action  of  peace  congresses 
and  international  tribunals  to  the  contrary,  it  is 
very  likely  that  a  determined  and  aggressive  foe 
would  ultimately  assail  after  issuing  due  warnings 
commanding  immediate  removal  of  all  non-com- 
batants, such  warnings  to  be  disregarded  at  the 
peril  of  the  party  attacked.  For  in  the  last  analy- 
sis of  the  bitterness  of  conflict  between  militant 
nations,  wars  are  fought  less  by  rules  than  to  win 
victories. 

In  the  face  of  such  tremendous  improvement  in 
mechanisms  for  the  destruction  of  life  and  prop- 
erty— without  which  war  cannot  be  successfully 
waged,  the  view  that  warfare  can  continue  indefi- 
nitely, in  a  world  of  civilized  and  intelligent  beings 
constantly  growing  more  civilized  and  more  intelli- 
gent, is  an  incredible  one.  Altogether  more  likely 
than  this  indefinite  continuation  of  war,  or  such 
voluntary  disarmament  and  arbitration  as  is  pro- 
posed by  idealists,  seems  an  unavoidable  and  en- 
forced arbitration,  imposed  upon  all  by  concerted 
action  of  the  great  powers  of  the  world,  which 
instead  of  maintaining  individual  armies  whose 
military  equipments — land,  naval,  and  aerial — will 
be  pitted  against  one  another  will  pool  their  forces 
for  the  maintenance  of  an  international  policing 
force  to  compel  arbitration  of  international  ques- 
tions, and  to  punish  terribly  such  benighted  nations 
as  may  have  the  hardihood  to  assert  militant 
dissent  from  the  prescriptions  of  the  intelligent 
majorities  of  civilization. 

Almost  as  significant  as  its  power  for  de- 


432  VEHICLES  OF  THE  AIR 

struction  is  the  invulnerability  of  the  aeroplane. 
Though  without  armor  or  any  corresponding  pro- 
tection, yet,  operated  in  fleets,  and  if  necessary 
under  cover  of  night,  no  one  familiar  with  modern 
gunnery  or  the  use  of  firearms  needs  to  be  told 
how  utterly  difficult  and  impracticable  will  be 
found  all  schemes  for  winging  the  aerial  vehicles. 
It  is  difficult  enough  to  hit  a  fixed  target  from  a 
substantially-mounted  weapon  after  the  range  has 
been  accurately  found.  It  is  more  difficult  to  strike 
a  moving  target  on  the  ground,  or  afloat  on  the 
water,  though  even  in  these  cases  the  restriction 
of  the  movement  to  a  horizontal  plane  and  the  pos- 
sibility of  correcting  errors  in  the  determination 
of  the  range  by  noting  the  splash  in  the  water,  or 
dust  thrown  up,  is  a  great  help.  But  to  strike  a 
vehicle  moving  through  the  air,  capable  of  ex- 
traordinary celerity  in  maneuvering,  capable  of 
three-dimensional  travel — up  and  down  as  well  as 
in  all  lateral  directions — and  with  no  means  what- 
ever of  finding  range,  can  never  happen  except  by 
the  purest  of  pure  accidents.  And  when  it  does 
happen  its  effect  upon  the  enemy's  strength  is  so 
certain  to  be  so  utterly  trivial — involving  the  de- 
struction of  no  more  than  a  few  hundred  dollars' 
worth  of  machinery  and  the  lives  of  not  more  than 
one  or  two  individuals — that  its  futility  as  a  means 
of  winning  a  victory  is  almost  too  evident  to 

require  discussion. 

SPORT 

Under  the  heading  of  this  much  abused  term 
can  be  perhaps  fairly  characterized  the  utilization 


FIGURE  225. — Scale  Drawings  of  Montgomery  Glider.       This    machine    is    exceedingly     sin 
though  as  in  the  case  of  all  aeronautical  apparatus  only  the  most  substantial  and  well-consic 
detail  construction  is  to  be  tolerated  if  safety  is  to  be  assured.    The  framework  consists  prim 
of  the  two  light  upper  bars  0  0,  terminating  in  the  spars  /  /,  and  of  the  heavier  bottom  ba 
connected  by   the   four   slanting  vertical  members  EH.     Each  of  the  two  main  wing  frames 
sists  of  two  wing  bars  attached  on  top  of  0  0,  and  bearing  on  their  under  sides  58  equally-sp 
curved  ribs  that  pass  through  pockets  sewed  into   the   single   surface   of  light   rubberized  sil 
percale  that  is  considered  the  preferable  material  for  the  wing  covering.     The  front  bar  of 
wing  is  firmly  lashed  to  00,  rigidly  trussed  into    a    pronounced    arch    by    the    wires    FFF, 
braced  by  the  masts  G  G,  but  the  rear  bars  are  divided  at   Q  Q   so   that  they  hinge   over  0  0 
droop  loosely  at  their  ends  to  a  level  considerably  below  that  of  the  front  bars.     They  are, 
ever,  prevented  from  lifting  above  a  certain  point  by  the  control  cords  E  E,  which  run  over  pu 
as  shown  and  are  attached  to  the  stirrup  bar  H,   by  means  of  which  the  operator  controls  the  d< 
with  his  feet.     When  in  the  air  the  droop  or  arch  of  the  wings  is  not  as  pronounced  as  show 
the  drawings,  which  show  the  machine  at  rest.     The  operator  sits  astride  the  seat  P  and  steer 
pressing  on  one  side  or  the  other  of  the  stirrup  bar,    the    cords    from    which    are    so    crossed 
pressure  with  the  right  foot  pulls  down  the  rear  edges  of  the  left  wing  ends,  and  vice  versa, 
manipulation  may  be  also  used  as  a  balancing  control,  but  equilibrium  is  maintained  chiefly  by 
automatic  effect  of  the  very  large  fin  surface  C,  which   though   it   moves   up   and   down   with 
rudder  D  has  no  lateral  movement.     In  addition  to  the  dissimilar  twisting  or  warping  of  the  i 
ends  by  pressing  down  on  one  side  or  the  other  of  the  stirrup  bar,  by  pressing  down  on  both 
simultaneously  all  the  rear  wing  tip  edges  are  drawn  down  together — a  manipulation  that  set: 
a  very  effective  braking  action,  by  which  the  machine  can  be  brought  to  land  so  lightly  that 
operator  is  not  even  jarred.     In  addition  to  these  control  movements  there  is  another,  by 
down  the  pulleys  over  which  the  cords  to  the  wing  B  are  passed,  through  the  action  of  which 
whole  angle  of  the  rear  wing  can  be  changed  in  relation  to  that  of  the  front  wing,  thus  affor 
control  over  the  longitudinal  equilibrium  by  an  elevator-like  action  of  the  two  wings  in  relatio 
each   other.     The   horizontal   tail   surface   D,   proximate   to   the  center   of  the   rear   edge  of  1 
controlled  by  the  cords  J  K,  which  are  attached  to    the    wooden    clamp    L,    automatically    lo 
by   the   effect   of  the   angular   pull  upon   it  in   any  position  at  which  it  may  be  placed  on  the 
tionary  wire  K,  which  runs  from  one  of  the  bars  0  to  the  bar  N. 

The  ribs  of  this  machine  should  be  made  of  clear,  well-seasoned  spruce,  i  inch  wide  and  -fa 
deep,  arid  ^eg/et  r£b  must  be  made  of  two  pieces  glued  together  under  pressure  in  a  form,   so 
they  'wmr  Irbld'-tne  requisite  curve.     The  wing  bars  are  best  made  of  hickory,  about  1£  inchei 
If  inchersr  at  rtheir' centers,  and  tapered  to  about  half  this  section  at  the  ends.     The  frame  bars 
'fiffri  1>3  r(>£  spr.u'ee'y-  aifout  1 J  inches  by  2  inches  at  their    centers    and    tapered    to    their    ends — i 
"smaller  size  forward  than  at  the  rear.     N  is  likewise  about  !£  inches  thick,  and  may  be  as 
as  3J  inches  at  the  center.     The  tail  framing  is  of  light  wood  edges  stayed  by  wires  arranged 
the  spokes  in  a  bicycle  wheel.    The  machine  weighs  about  40  pounds.    All  dimensions  are  in  incht 


35-><- — vo  — ><—  -56 


T 


. 


MISCELLANY  433 

of  aerial  vehicles  for  pleasure  travel  in  one  man- 
ner and  another. 

Aeroplane  contests  already  have  provided 
thrills  sufficient  to  satisfy  the  most  blase  audiences, 
and  in  the  near  future,  when  the  speeds  made  seem 
certain  to  become  vastly  higher  than  any  that  have 
been  maintained  with  any  other  types  of  vehicles, 
they  will  become  even  more  spectacular.  More- 
over the  element  of  safety  in  such  contests  is  much 
greater  than  might  be  supposed — probably  much 
greater  than  in  automobile  racing,  which  has  been 
responsible  for  a  truly  appalling  list  of  fatalities. 
This  is  because,  while  land  vehicles  are  built  to 
travel  on  land,  they  are  built  to  do  so  only  on  espe- 
cially prepared  courses,  so  when  an  automobile 
leaves  the  road,  or  a  rail  vehicle  leaves  the  rails 
imminent  and  terrible  dangers  are  introduced, 
whereas  in  the  case  of  the  vehicle  designed  to 
travel  in  the  air — even  a  plunge  to  the  earth  in- 
volves movement  through  rather  than  away  from 
its  natural  route,  with  corresponding  chance  if  the 
vehicle  be  well  designed  of  regaining  its  normal 
control  and  of  recovering  its  equilibrium,  or,  at 
worst,  of  landing  without  injury  to  the  occupant. 

MAIL  AND  EXPRESS 

The  first  commercial  applications  of  flying  ve- 
hicles must  inevitably  be  to  the  transport  of  light 
commodities,  such  as  it  is  desirable  to  convey  at 
great  speeds  and  which  can  be  paid  for  at  high  rates 
per  unit  of  weight. 

The  ideal  service  of  this  character  would  be 


434  VEHICLES  OF  THE  AIR 

that  of  a  number  of  vehicles  traversing  a  route  of 
the  maximum  distance  possible  to  accomplish  with- 
out alighting,  dropping  mail  bags  on  clear  areas 
where  watchers  would  be  waiting  to  receive  them. 

NEWS  SERVICE 

Besides  for  the  distribution  of  mail  and  ex- 
press, aerial  vehicles  may  lend  themselves  to  the 
distribution  of  newspaper  matrices  and  illustra- 
tions prepared  at  central  points  for  quick  trans- 
mission to  rural  newspaper  plants,  not  provided 
as  at  present  with  expensive  editing  and  composing 
forces,  but  chiefly  equipped  with  stereotyping  and 
printing  facilities. 

EFFECTS  OF  LOW  COST  AND  MAINTENANCE 

Most  important  factors  in  the  further  improve- 
ment and  the  future  applications  of  aerial  vehicles 
are  certain  to  be  the  lower  first  and  maintenance 
costs  that  are  reasonably  to  be  anticipated  if  what 
has  been  already  done  is  any  criterion. 

With  some  of  the  most  efficient  modern  aero- 
planes it  has  been  proved  possible  to  transport 
weights  of  as  great  as  1,600  pounds  for  distances 
of  twelve  and  fifteen  miles  on  a  gallon  of  gasoline — 
a  result  that  compares  most  favorably  with  even 
the  best  secured  with  modern  automobiles,  espe- 
cially at  anything  like  similar  speeds — in  the  neigh- 
borhood of  40  or  45  miles  an  hour. 

An  inevitable  result  of  low  first  and  mainte- 
nance costs  must  be  the  extensive  acquisition  of 
aerial  vehicles  by  all  manner  of  individuals — indi- 


FIGURE  226. — Side  View  of  Montgomery  Double  Monoplane  Glider.  This  machine  was 
probably  built  on  more  scientific  principles  than  any  other  so  far  constructed.  On  at  least 
three  occasions  operators  have  deliberately  turned  side  somersaults  with  it,  besides  which 
many  descents  have  been  safely  made  from  heights  ranging  up  to  4,000  feet,  at  speeds  said 
to  have  ranged  as  high  as  68  miles  an  hour.  Its  equilibrium  is  so  positive  that  it  auto- 
matically rights  itself  when  released  upside  down  in  the  air. 


FIGURE  227. — Side  View  of  Small,  Power-Propel lod  Montgomery  Double  Monoplane.  This 
machine  has  a  wing  spread  of  26  feet;  an  area  of  250  square  feet,  and  weighs  from  400  to  450 
pounds,  including  the  weight  of  the  operator  and  the  fuel.  It  flies  at  a  speed  of  over  30  miles 
an  hour  with  less  than  six  horsepower,  and  employs  more  deeply  cambered  curves  than  have 
been  successfully  used  in  any  other  machine.  Its  stability  is  inherent  in  the  form  of  its 
surfaces  rather  than  dependent  upon  the  manipulation  of  balancing  devices,  so  that  if  dropped 
upside  down  it  will  invariably  right  itself  and  commence  gliding  with  a  fall  of  not  over 
four  or  five  times  the  span  of  its  wings.  The  large  vertical  surface  at  the  rear  has  no  move- 
ment sidewise,  being  a  stabilizing  fin,  not  a  rudder. 


• 


MISCELLANY  435 

viduals  of  a  class  today  quite  unable  to  afford  even 
the  most  inexpensive  automobiles.  More  than  this, 
the  aerial  vehicles  not  being  confined  to  roads  or 
highways  of  any  kind,  there  is  not  the  slightest 
possibility  either  of  monopolies  or  of  limitations  in 
their  use  other  than  the  direct  physical  limitations 
imposed  by  such  mechanical  imperfections  as,  of 
course,  can  never  be  wholly  eradicated,  however 
they  may  be  minimized. 

GENERAL  EFFECTS 

The  wide  introduction  of  aerial  vehicles  into 
the  hands  of  the  general  public,  if  it  ever  occurs, 
and  it  seems  more  than  likely  that  it  will  occur, 
cannot  fail  to  exert  consequent  influences  of  the 
profoundest  importance  upon  innumerable  phases 
and  regulations  of  the  accepted  social  order.  The 
very  independence  of  movement  which  only  an 
aerial  vehicle  can  possess  will  in  itself  unfailingly 
modify  the  whole  structure  of  civilization. 

A  most  certain  result  of  the  new  condition  in 
human  affairs  following  upon  man's  achievement 
of  flight  will  be  the  inevitable  effect  on  laws  and 
customs.  Assertions  to  the  contrary  notwith- 
standing, it  is  impossible  to  see  how  either  exclu- 
sion laws  or  customs  laws  (except  perhaps  in  the 
case  of  very  heavy  commodities)  are  going  to  be 
at  all  enforceable  in  the  coming  era  of  aerial  navi- 
gation. The  boundaries  of  every  nation  in  the 
world,  except  possibly  those  of  the  most  densely 
populated,  will  absolutely  cease  to  exist  as  barriers 
that  can  be  policed  and  safeguarded  against  pro- 


436  VEHICLES  OF  THE  AIR 

grossing  humanity's  perfectly  natural  disposi- 
tion to  travel  and  communicate  without  let  or 
hindrance. 

A  more  sinister  aspect  of  this  time  to  come  is 
the  tremendous  facility  with  which  the  aerial 
vehicle  will  lend  itself  to  the  perpetration  of  crime 
with  almost  perfect  assurance  for  the  criminal  of 
escape  from  punishment  and  other  consequences. 
Indeed,  as  a  police  problem  the  aeroplane  bids  fair 
to  become  far  more  serious  than  the  much-appre- 
hended and  now-realized  noiseless  gun.  Neverthe- 
less, no  one  with  any  real  optimism  can  long  believe 
that  progress  in  science  and  invention  can  have 
any  permanent  injurious  or  detrimental  effect  on 
human  affairs.  Perhaps  the  solution  will  be  a 
greater  effort  on  the  part  of  society  as  a  whole, 
and  especially  upon  the  part  of  the  now  more 
powerful  and  arrogant  elements  within  it,  so  to 
ameliorate  and  improve  the  conditions  of  the 
" criminal  classes",  so-called,  and  more  particu- 
larly of  the  poverty-stricken  classes — from  which 
nearly  all  criminals  are  recruited  by  the  reac- 
tions of  oppressive  environments — that  less  crimes 
will  be  committed  not  because  of  policing  and  pun- 
ishment, but  because  of  reduced  incentive. 

RADII  OF  ACTION 

Since  almost  the  only  limitation  at  the  present 
time  in  the  way  of  indefinitely-continued  flight, 
even  with  present  machines — and  barring,  of 
course,  the  matter  of  more  or  less  violent  storms — 
is  the  difficulty  of  carrying  sufficient  supplies  of 


MISCELLANY  437 

fuel,  it  is  clear  that  as  more  efficient  propellers  and 
engines,  or  surfaces  affording  given  sustention 
with  smaller  head  resistances,  may  be  developed, 
the  radii  of  action  is  certain  to  be  increased  in 
proportion. 

INFLUENCE  OF  WIND 

In  the  case  of  water  travel,  excepting  in  rare 
instances  of  river  navigation  through  rapids 
or  of  navigation  through  narrow  channels  with 
rapid  tidal  flows,  the  currents  in  navigable  waters 
are  not  of  sufficient  speed  materially  to  help  or 
hinder  vessels  passing  through  them.  With  the 
atmosphere  the  case  is  quite  the  other  way.  In 
this  lightest  of  earth's  traversable  media  move- 
ments of  the  air  in  the  form  of  wind,  of  velocities 
considerably  in  excess  of  the  best  speeds  that  have 
been  attained  with  aeroplanes,  are  common.  In 
fact,  it  is  a  fair  assertion  that  winds  of  even  as 
high  as  100  miles  an  hour — approximately  twice 
as  fast  as  the  greatest  present  aeroplane  speeds — 
are  occasionally  to  be  reckoned  with,  even  though 
they  will  not  be  commonly  encountered  and  never 
will  be  flown  in  when  such  flight  is  avoidable. 

DEMOUNTABILITY 

Apparently  not  satisfied  with  the  altogether 
sufficient  difficulties  of  making  flying  machines  to 
fly,  more  than  one  inventor  has  in  addition  at- 
tempted to  construct  such  vehicles  in  folding  form 
— probably  inspired  by  the  beautiful  perfection  of 
the  bird's  wing  mechanism — with  the  idea  of  simi- 


438  VEHICLES  OF  THE  AIR 

larly  quickly  stowing  the  wings  and  other  parts 
of  the  machine  in  compact  and  portable  shape. 

It  being  a  condition  involved  in  almost  any  con- 
ceivable aerial  vehicle  that  considerable  dimen- 
sions must  be  employed  because  of  the  necessity 
for  operating  in  one  way  or  another  upon  large 
areas  of  air,  there  is  much  to  be  said  in  favor  of 
any  scheme  that  seems  to  promise  a  compacter 
arrangement  of  the  vehicle  elements  when  the 
machine  is  at  rest  than  is  required  when  it  is  in 
the  air.  This  is  important  both  for  storage  and 
for  shipment  and,  as  has  been  suggested,  has  its 
counterpart  in  all  known  flying  creatures,  which 
without  exception  fly  with  surfaces  capable  of 
being  folded  more  or  less  out  of  the  way  when 
not  in  use. 

But  the  difficulties  in  the  way  of  making  reliable 
folding  wings  are  very  great — so  great  that  in  the 
present  state  of  the  art  it  seems  hardly  desirable 
to  attempt  overcoming  them  until  after  more 
perfect  and  dependable  results  are  secured  in  the 
more  vital  functioning  of  flying  mechanisms. 

Demountability,  however,  is  an  altogether  dif- 
ferent thing  from  folding,  this  term  implying  only 
the  ready  detachability  and  separation  of  different 
parts  with  corresponding  facility  in  reassembling. 
Several  very  successful  modern  aeroplanes  are 
made  demountable  in  greater  or  lesser  degree. 

A  further  advantage  of  demountability  is  the 
conversion  by  its  means  of  the  aerial  vehicle  into 
a  more  or  less  capable  road  vehicle.  Thus  the 
"  June  Bug"  of  the  Aerial  Experiment  Association, 


MISCELLANY  439 

with  its  wings  off,  was  still  capable  of  rolling  along 
on  its  wheeled  starting  gear.  In  this  condition  it 
proved  capable  of  speeds  as  high  as  forty-five  miles 
an  hour,  simply  run  on  the  road  under  the  thrust 
of  its  own  propeller. 

In  the  case  of  the  "June  Bug",  however,  the 
wings  when  taken  off  were  not  carried  with  the 
machine,  making  the  scheme  employed  in  the  most 
recent  Bleriot  monoplanes  and  illustrated  in  Fig- 
ures 245,  246,  and  247,  altogether  superior.  As 
is  shown  in  these  illustrations,  the  two  main  wings 
are  simply  detached  from  their  proper  places  on 
the  fuselage  and  tied  compactly  against  the  sides, 
so  that  the  machine,  carrying  all  of  its  flying  ele- 
ments, makes  an  excellent  vehicle  for  running  on 
good  roads — a  most  desirable  feature  in  case  a 
landing  is  made  on  a  bad  surface  and  it  becomes 
necessary  to  prospect  about  before  a  suitable  place 
for  starting  is  found. 

Undoubtedly  this  matter  of  demountability, 
especially  as  machines  become  more  practical  and 
more  numerous,  is  one  that  will  merit  further  con- 
sideration by  designers,  with  the  result  that  pres- 
ent-day shortcomings  will  decreasingly  handicap 
future  progress. 

PASSENGER  ACCOMMODATION 

Accommodation  for  passengers  in  most  of  the 
flying  machines  so  far  built  has  been  of  a  more  or 
less  makeshift  character,  it  being  appreciated  that 
the  most  essential  thing  as  yet  is  to  produce  ma- 
chines that  will  fly,  leaving  the  minor  question  of 


440  VEHICLES  OF  THE  AIR 

comfortable  passenger  accommodations  for  subse- 
quent solution. 

SEATS 

About  the  least  that  can  be  provided  in  the 
way  of  passenger  accommodation  is  some  sort  of 
seating  arrangement.  So  far  the  most  of  such 
seats  have  been  of  the  most  elementary  construc- 
tion, as  is  suggested  in  the  illustrations  throughout 
these  pages.  Lately,  however,  some  of  the  more 
advanced  craft  are  appearing  with  very  comfort- 
able arrangements  for  seating  the  operator,  as  is 
particularly  evidenced  in  the  boat-like  cockpits 
provided  in  the  Bleriot,  Antoinette,  and  R.  E.  P. 
machines,  as  shown  in  Figures  249,  250,  and  252, 
respectively. 

HOUSING 

As  proved  the  case  in  the  development  of  the 
automobile,  it  probably  will  be  only  a  short  step 
from  the  provision  of  comfortable  seats  to  the  pro- 
vision of  enclosures  for  these  seats,  housing  the 
operator  and  passengers  from  the  weather  and 
from  the  wind  of  the  movement  through  the  air. 

UPHOLSTERY 

Cushioning  of  the  bottoms  and  backs  of  seats 
is  a  luxury  that  has  already  found  application  to 
the  aeroplane,  though  cane  and  wooden  chair  seats 
are  found  rather  lighter. 

Pneumatic  Cushions,  of  covering  materials  with 
rubber  or  other  gasproof  linings,  inflated  with  air, 
are  much  used  in  boats  and  yachts  and  to  some 
extent  for  the  seats  of  automobiles.  Pneumatic 


FIGURE  248. — Wicker  Chair  and  Foot  Control  of  Ailerons  in  Sommer's  Farman  Biplane. 


FIGURE  249. — Cockpit  of  Bleriot  Monoplane  Number  XI. 


MISCELLANY 


441 


cushions  are  exceedingly  light,  constitute  very  sat- 
isfactory life  preservers  in  case  of  descent  into 
water,  and  are  sufficiently  durable  to  make  them 
thoroughly  practical.  It  therefore  seems  reason- 
able to  regard  them  as  an  ideal  type  of  aerial- 
vehicle  upholstery. 

HEATING 

While  it  can  be  considered  hardly  reasonable, 
in  the  present  status  of  aeronautical  engineering,  to 
transport  special  devices  for  keeping  the  passen- 
gers warm  as  is  done  in  rail  and  water  vehicles 
and  even  in  auto- 
mobiles, there  is 
another  road  to  the 
provision  of  such 
comforts  without 
materially  adding 
to  the  weight  or 
complication. 

By  the  Exhaust 
gases  which  must  be 
emitted  from  all  internal-combustion  engines, 
which  are  very  hot,  and  which  must  be  disposed  of, 
it  is  possible  to  secure  a  considerable  heating  effect 
in  a  very  simple  and  practical  way. 

A  typical  exhaust  heater  such  as  is  to  some 
extent  used  for  automobiles  is  illustrated  in  Figure 
255,  in  which  the  principle  is  simply  that  of  a 
muffler-like  apparatus  beneath  the  passengers' 
feet,  and  through  which  the  gases  from  the  engine 
are  caused  to  follow  the  intricate  course  indicated 
hy  the  arrows  and  determined  by  the  numerous 


FIGURE  255. — Suggested  Use  of  Exhaust 
Gases  to  Heat  Foot  Warmer. 


442  VEHICLES  OF  THE  AIR 

baffle  plates,  finally  making  their  exit  to  the  rear. 
The  valve  provides  means  of  throwing  the  heater 
in  and  out  of  action. 

PARACHUTES 

The  use  of  parachutes  antedates  the  invention 
of  the  balloon,  it  being  on  record  in  Loubere's 
"History  of  Siam"  that  250  years  ago  an  oriental 
inventor  entertained  Siamese  royalty  by  leaps 
from  great  heights  with  two  parachutes  attached 
to  a  belt.  In  1783  M.  le  Normand,  of  Lyons, 
France,  proposed  the  use  of 
parachutes  as  fire  escapes,  and 
demonstrated  their  utility  by 
successfully  descending  with 
one  from  the  top  of  a  high  build- 
ing in  that  city.  The  aeronaut 
Blanchard  was  the  first  to  con- 
ceive of  using  the  parachute  in 
FlQUB%b2ute'~Para"  ballooning,  and  in  1783  he  tested 
one  by  attaching  it  to  a  basket 
in  which  was  placed  a  dog,  whereupon  the  whole 
being  released  at  a  considerable  height  settled  to 
the  ground  in  safety.  In  1793  he  descended  him- 
self from  a  balloon,  but,  though  the  fall  was  fairly 
retarded,  he  nevertheless  suffered  a  broken  leg  as 
a  result  of  his  daring.  On  October  22,  1797,  the 
first  really  successful  parachute  jump  was  made 
by  Andre  Jaques  Garnerin  from  a  balloon  a  mile 
and  a  quarter  high  over  the  plain  of  Monceau,  near 
Paris. 

Modern  parachutes,  such  as  that  illustrated  in 


MISCELLANY  443 

Figure  256,  are  made  from  twenty  to  thirty  feet 
in  diameter,  with  a  hole  at  the  center  to  prevent 
oscillation,  and  without  framing  of  any  kind,  the 
series  of  cords  by  which  the  surface  is  attached  to 
the  weight  serving  to  preserve  the  umbrella-like 
form  essential  to  a  safe  descent,  and  produced  pri- 
marily by  the  air  pressure.  They  sustain  about 
half  a  pound  to  the  square  foot.  Parachutes 
capable  of  safely  carrying  a  man  have  been  made 
of  less  than  twenty  pounds  in  weight. 

DESIGNING 

In  the  design  of  aerial  vehicles  an  exact  science 
is  becoming  rapidly  established,  with  its  recog- 
nized engineering  practises  and  the  possible  freak- 
ish departures  therefrom  that  are  found  to  exist 
in  all  departments  of  technical  endeavor. 

For  the  benefit  of  the  intending  designer  or 
experimenter,  however,  it  is  possible  at  the  present 
time  only  to  emphasize  the  important  point  that 
this  field  of  engineering  is  one  in  which  nothing 
less  than  a  broad  and  practical  engineering  knowl- 
edge can  suffice  to  produce  results.  Were  suc- 
cessful aerial  vehicles  to  have  been  produced  by 
the  rule-and-thumb  methods  that  have  been  more 
or  less  advantageously  employed  in  most  other 
fields  of  mechanical  engineering,  successful  flying 
or  at  least  gliding  machines  would  have  been  in- 
vented two  thousand  years  ago,  for  failure  in  the 
past  has  been  due  not  to  lack  of  effort  or  facilities, 
out  to  the  inadequate  technical  equipment  possessed 
be  experimenters.  The  conclusion  is  that  the  ordi- 


444  VEHICLES  OF  THE  AIR 

nary  amateur  will  do  best  by  closely  copying 
proved  constructions. 

TESTING  AND  LEARNING 

In  testing  new  flying  machines,  and  even  in 
learning  to  operate  ones  of  established  qualities, 
there  are  a  number  of  things  to  be  considered  that 
are  a  little  different  from  the  conditions  surround- 
ing the  tests  of  other  mechanisms  and  the  operation 
of  other  vehicles. 

Thus  failure  of  an  experiment  with  a  mechan- 
ism of  this  type  is  likely  to  be  not  a  mere  mechani- 
cal failure,  but  also  .may  readily  result  in  injury 
to  or  the  death  of  its  operator  unless  ingenious 
and  well-considered  precautions  are  taken  to 
assure  a  maximum  prospect  of  safety. 

Likewise,  for  a  beginner  to  attempt  to  drive  a 
machine  even  of  a  type  known  to  be  well  capable 
of  flying,  the  attempt  can  easily  become  most  dan- 
gerous business  if  gone  at  in  a  reckless  manner. 

LEAENING  FEOM  TEACHER 

By  all  means  the  best  method  of  learning  to 
operate  a  flying  machine  is  that  possible  when  the 
machine  can  carry  two  people  and  the  pupil  can 
thus  take  his  first  rides  with  an  expert. 

PRACTISE  CLOSE  TO  THE  SURFACE 

When  an  instructor  is  not  to  be  had,  as  in  the 
case  of  a  new  machine  that  no  one  knows  how  to 
fly— not  even  that  it  will  fly — or  of  a  machine  that 
will  carry  only  one  person,  it  becomes  possible  for 
the  operator  to  acquire  the  necessary  dexterity 


MISCELLANY  445 

only  by  practise.  Such  practise  is  most  readily 
and  speedily  secured  by  the  use  of  large  level  areas 
over  which  the  machine  can  be  run  on  its  wheeled 
or  other  running  gear,  with  "low  jumps"  into  the 
air  that  extend  to  greater  and  greater  lengths  as 
the  experimenter  becomes  proficient. 

Practise  over  Water  presents  a  number  of  very 
great  advantages  over  any  other  sort  of  practise 
that  can  be  had,  there  being  in  the  first  place  the 
level  and  almost  ideally  smooth  surface,  in  addition 
to  which,  if  it  comes  to  falling,  water  is  better 
to  fall  upon  than  hard  ground.  Drowning  is  suffi- 
ciently guarded  against  by  the  circumstance  that 
almost  all  modern  machines  have  sufficient  wood  in 
their  construction  to  float  them,  besides  which  they 
can  be  fitted  with  inflated  fabric  floats  and  the 
operator  provided  with  a  life  preserver. 

MAINTAINING  HEADWAY 

If  there  is  any  one  point  in  the  operation  of 
most  modern  aeroplanes  that  calls  for  especial 
emphasis,  it  is  the  most  imperative  necessity  for 
always  maintaining  headway,  since  the  forward 
movement  through  the  air  is  all  that  sustains  the 
machine  in  the  air. 

LANDING 

Just  at  the  moment  of  landing,  it  is  possible 
with  most  machines  to  execute  an  abrupt  upward 
steering  movement,  with  the  effect  that  the  wing 
surfaces  strike  the  air  at  a  very  steep  angle  of  inci- 
dence, causing  them  to  act  as  a  sort  of  brake.  This 
maneuver  will  be  better  appreciated  if  its  relation 


446  VEHICLES  OF  TEE  AIR 

is  realized  to  the  similar  maneuver  of  birds,  which 
always  at  the  moment  of  alighting  oppose  the  full 
areas  of  their  wings  to  the  direction  of  travel. 

AERIAL  NAVIGATION 

Though  in  its  general  meaning  this  is  the  sub- 
ject to  which  the  whole  of  this  book  relates,  in  a 
more  specific  sense  it  is  to  be  applied  to  the  details 
of  operating  and  driving  aerial  vehicles. 

Considered  from  this  standpoint  aerial  naviga- 
tion, like  water  navigation,  presents  its  special  and 
peculiar  problems. 

This  being  the  situation  there  can  as  yet  be  no 
established  science  of  aerial  navigation,  but  it  is 
nevertheless  possible  to  formulate  some  of  the 
essential  principles  of  such  a  science  and  to  per- 
ceive many  of  the  factors  in  the  problem. 

FLYING  HIGH 

Flying  very  high  so  far  does  not  seem  to  have 
met  with  the  approval  of  any  but  the  more  reckless 
experimenters,  and  in  no  case  recorded  at  this 
writing  has  any  power-driven  aeroplane  ascended 
more  than  4,600  feet  high,  while  ascents  even  to 
this  and  to  other  considerable  altitudes  have  been 
made  not  so  much  from  any  necessity  for  flying 
great  heights,  as  under  the  more  frequent  spur  of 
prize  competitions.  The  longest  sustained  flight 
made  previous  to  this  writing,  that  of  Farman  at 
Rheims,  on  August  27, 1909,  was  at  a  height  rarely 
exceeding  ten  feet  from  the  ground. 

Steadier  Air  than  is  in  most  cases  to  be  found 


MISCELLANY 


447 


nearer  the  ground  is  well  established  to  exist  at 
greater  heights,  particularly  over  surfaces  that  are 
irregular  or  built-up. 

Choice  of  Landing,  in  case  of  motor  breakdown 
or  other  reason  for  descent,  is  greatly  broadened 
by  flight  at  considerable  altitudes.  This  will  be 


FIGURE  257. — Effect  of  Height  Upon  Choice  of  Landing.  Note  that  the 
machine  g  has  a  much  greater  area  than  the  machine  h,  down  to  which  it 
can  glide  in  case  of  motor  failure,  its  angle  of  descent  being  indicated  by 
the  solid  lines  c  c,  those  at  f  f  being  for  the  machine  h.  The  dotted  lines 
d  d  and  e  e  show  the  distortion  from  the  circle  upon  which  landing  i3 
possible,  when  there  is  wind  blowing  in  the  direction  of  the  arrow. 

more  readily  understood  from  reference  to  A  and 
Bf  Figure  257,  in  which  the  aeroplanes  g  and  h  can 
normally  descend  in  calm  air  on  gliding  angles 
represented  by  the  solid  lines  c  and  f,  thus  afford- 
ing choice  of  landing  anywhere  within  a  circle  of 
a  diameter  proportionate  to  the  height  of  the  start 
and  the  flatness  of  the  angle  of  descent. 

FLYING  LOW 

Flying  low,  while  introducing  safeguards  also 
introduces  dangers,  especially  if  attempts  be  made 
to  fly  low  over  rough  country,  in  which  the  chance 


448  VEHICLES  OF  THE  AIR 

of  striking  obstacles  with  the  machine  flying  reli- 
ably might  easily  become  more  serious  than  the 
danger  of  a  fall  from  the  remoter  possibility  of 
some  desperate  and  unexpected  breakdown. 

In  all  probability  the  lowest  regular  flying  of 
the  future  will  be  over  water  areas,  where  the  sur- 
face is  level  and  uniform  and  presents  no  obstacles 
to  throw  the  atmosphere  into  irregular  motions. 

Falling  is  one  of  the  possible  dangers  that  can 
be  minimized  by  low  flight,  but,  as  has  been  already 
explained,  all  practical  modern  aeroplanes  being 
essentially  stable  as  gliders  even  with  their  motors 
inoperative  there  is  apparently  very  little  danger 
of  abrupt  falls. 

Striking  Obstacles  is  a  much  more  serious  dan- 
ger, for  there  is  not  only  the  possibility  of  running 
into  obstacles  not  seen  in  time  because  of  the 
attempt  to  skim  over  them  too  closely;  there  is  also 
the  danger  while  flying  low  of  being  thrust  enough 
out  of  the  intended  course  by  a  sudden  wind  gust 
to  cause  such  an  accident. 

Vortices  and  Currents  in  the  air  are  well  dem- 
onstrated to  exist  in  proximity  to  all  terrestrial 
objects  during  winds,  and  are  of  a  violence  and 
complexity  of  motion  varying  with  the  strength  of 
the  wind  and  the  character  of  the  obstacles. 
Travel  through  such  vortices  and  currents  ob- 
viously is  much  more  dangerous  than  travel 
through  uniform  air,  a  fact  that  has  already  been 
discovered  by  some  of  the  pioneers  in  aerial  navi- 
gation. An  interesting  example  was  remarked  by 
Glenn  Curtiss  at  Rheims,  in  1909,  when  over  one 


FIGURE  250. — Seating  Arrangement  and  Control  System  of  Antoinette  Monoplane. 


FIGURE  251. — Sling  Seat  of  Captain  Ferber's  Biplane. 


MISCELLANY  449 

part  of  the  course  he  found  the  air  to  be  "  literally 
boiling",  as  he  expressed  it. 

TERRESTRIAL  ADJUNCTS 

In  the  impending  utilization  of  the  air  as  a 
highway  for  sporting  and  military  operations  and 
probably  for  the  conveyance  of  mail  and  express 
matter,  if  not  absolutely  as  a  medium  for  all  kinds 
of  passenger  and  commercial  traffic,  it  is  inevitable 
that  systems  of  signalling  from  the  earth's  surface 
to  the  aerial  vehicles  must  be  devised. 

An  ideal  means  would  be  the  use  of  wireless 
telegraphy  but  this  in  its  present  development 
comes  nearer  to  permitting  the  aerial  craft  to 
receive  messages  than  to  send  them,  because  of  the 
much  greater  weights  of  sending  apparatus. 

SIGNALS 

The  kinds  of  information  that  it  is  likely  to  be 
most  essential  for  the  future  aerial  pilot  to  have 
from  terrestrial  stations  will  be  data  in  regard  to 
his  location,  measurements  of  wind  direction  and 
velocity,  weather  forecasts,  etc.  To  these  ends  it 
doubtless  will  prove  feasible  to  establish  lettered 
or  other  landmarks  easily  recognized  by  day,  with 
systems  of  lights  to  serve  the  same  purpose  by 
night.  The  idea  of  painting  signals,  and  even  the 
flying  machines  themselves,  with  luminous  paints 
capable  of  emitting  a  clearly-visible  glow  in  the 
dark  has  been  suggested,  and  doubtless  could  be 
developed  into  a  considerable  safeguard  against 
accident  and  a  means  of  greatly  facilitating  navi- 


450 


VEHICLES  OF  THE  AIR 


gation.  The  most  recent  and  interesting  work 
along  this  line  has  been  done  by  William  J.  Ham- 
mer, of  New  York,  the  well  known  physicist,  who 
is  secretary  of  the  Aeronautic  Society. 

Fog  Horns  and  Whistles  would  provide  a  means 
of  signalling  weather  and  wind  conditions,  of 
transmitting  orders,  etc.,  at  times  when  view  of 
the  earth's  surface  might  be  obscured  by  low-lying 
fogs  or  clouds. 

The  United  States  Weather  Bureau  system  of 


FIGURE  258. — United  States  Weather  Signals.  A  denotes  fair  weather; 
B,  general  rain  or  snow ;  C,  local  rain  or  sisow  ;  and  D,  a  rise  or  fall  in 
temperature,  according  to  whether  it  is  placed  above  or  below  the  other 
flag  displayed.  £  indicates  approach  of  a  cold  wave. 

weather  forecasting  by  means  of  simple  flag  com- 
binations could  be  readily  adapted  for  display 
on  horizontal  surfaces,  or  even  by  lights  at  night. 
For  use  in  rainy  or  foggy  weather,  along  sea 
coasts,  etc.,  the  United  States  Weather  Bureau  at 
present  announces  its  forecasts  by  means  of 
whistle  blasts,  one  long  blast  repeated  at  intervals 
meaning  fair  weather;  two  long  blasts  indicating 
general  rain  or  snow,  three  long  blasts  indicating 
local  rain  or  snow,  one  short  blast  indicating  lower 
temperature,  two  short  blasts  indicating  higher 
temperature,  and  three  short  blasts  indicating  a 
cold  wave.  The  long  blasts  are  of  from  four  to 
six  seconds  and  the  short  from  one  to  three. 


FIGURE  252. — Cockpit  and  General  Details  of  R.  E.  P.  Monoplane. 


FIGURE    253. — Latham's    Antoinette    Monoplane    in    the    English    Channel.     Showing    that 
suoh  a  machine  may  be  made  to  constitute  an  excellent  raft. 


MISCELLANY 


451 


PATENTS 

The  aeronautical  patent  situation  in  the  United 
States  is  a  very  interesting  one — so  interesting 
that  the  full  drawings,  specifications,  and  claims 
of  what  seem  the  two  most  important,  No.  821,393, 
to  Orville  and  Wilbur  Wright,  and  No.  831,173,  to 
John  J.  Montgomery,  are  here  reproduced  in  full. 

Other  United  States  patents  the  claims  of 
which  are  reprinted  herein  are  numbers  582,718, 
to  Chanute,  582,757,  to  Mouillard,  and  544,816,  to 
Lilienthal. 


Specification  and  Claims  of  Wright  Patent. 


No.  821,393. 


Filed  March  23,  1903. 


To  all  whom  it  may  concern: 

Be  it  known  that  we,  Orville  Wright 
and  Wilbur  Wright,  citizens  of  the  United 
States,  residing  in  the  city  of  Dayton,  county 
of  Montgomery,  and  State  of  Ohio,  have  in- 
vented certain  new  and  useful  Improvements 
in  Flying-Machines,  of  which  the  following  is 
a  specification. 

Our  invention  relates  to  that  class  of  fly- 
ing-machines in  which  the  weight  is  sustained 
by  the  reactions  resulting  when  one  or  more 
aeroplanes  are  moved  through  the  air  edge- 
wise at  a  small  angle  of  incidence,  either  by 
the  application  of  mechanical  power  or  by 
the  utilization  of  the  force  of  gravity. 

The  objects  of  our  invention  are  to  provide 
means  for  maintaining  or  restoring  the  equi- 
librium or  lateral  balance  of  the  apparatus, 
to  provide  means  for  guiding  the  machine 
both  vertically  and  horizontally,  and  to  pro- 
vide a  structure  combining  lightness,  strength, 
convenience  of  construction  and  certain 
other  advantages  which  will  hereinafter  ap- 
pear. 

To  these  ends  our  Invention  consists  In  cer- 
tain novel  features,  which  we  will  now  pro- 
ceed to  describe  and  will  then  particularly 
point  out  in  the  claims. 

In  the  accompanying  drawings,  Figure  1  is 
a  perspective  view  of  an  apparatus  embody- 
ing our  invention  in  one  form.  Fig.  2  is  a 
plan  view  of  the  same,  partly  in  horizontal 
section  and  partly  broken  away.  Fig.  3  is  a 
side  elevation,  and  Figs.  4  and  5  are  detail 
views,  of  one  form  of  flexible  joint  for  connect- 
ing the  upright  standards  with  the  aeroplanes. 

In  flying-machines  of  the  character  to 
which  this  invention  relates  the  apparatus  is 
supported  in  the  air  by  reason  of  the  contact 
between  the  air  and  the  under  surface  of  one 
or  more  aeroplanes,  the  contact-surface  be- 
ing presented  at  a  small  angle  of  incidence  to 
the  air.  The  relative  movements  of  the  air 
and  aeroplane  may  be  derived  from  the  mo- 
tion of  the  air  in  the  form  of  wind  blowing  in 
the  direction  opposite  to  that  in  which  the 
apparatus  Is  traveling  or  by  a  combined 
downward  and  forward  movement  of  the  ma- 
chine, as  in  starting  from  an  elevated  posi- 
tion or  by  combination  of  these  two  things, 
and  in  either  case  the  operation  is  that  of  a 
soaring-machine,  while  power  applied  to  the 
machine  to  propel  it  positively  forward  will 
eause  the  air  to  support  the  machine  In  a  slmi- 


Issued  Hay  28,  1906. 

Expires  May  22,  1923. 

lar  manner.  In  either  case  owing  to  the  va- 
rying conditions  to  be  met  there  are  numer- 
ous disturbing  forces  which  tend  to  shift 
the  machine  from  the  position  which  it  should 
occupy  to  obtain  the  desired  results.  It  is 
the  chief  object  of  our  invention  to  provide 
means  for  remedying  this  difficulty,  and  we 
will  now  proceed  to  describe  the  construction 
by  means  of  which  these  results  are  accom- 
plished. 

In  the  accompanying  drawings  we  hare 
shown  an  apparatus  embodying  our  invention 
in  one  form.  In  this  illustrative  embodi- 
ment the  machine  is  shown  as  comprising 
two  parallel  superposed  aeroplanes  1  and  2, 
and  this  construction  we  prefer,  although  our 
invention  may  be  embodied  in  a  structure 
having  a  single  aeroplane.  Each  aeroplane 
is  of  considerably  greater  width  from  side  to 
side  than  from  front  to  rear.  The  four  cor- 
ners of  the  upper  aeroplane  are  indicated  by 
the  reference-letters  a,  h,  c,  and  d,  while  the 
corresponding  corners  of  the  lower  aeroplane 
2  are  indicated  by  the  reference-letters  e>  f, 
g,  and  h.  The  marginal  lines  a  b  and  e  f  indi- 
cate the  front  edges  of  the  aeroplanes,  the 
lateral  margins  of  the  upper  aeroplane  are  in- 
dicated, respectively,  by  the  lines  a  d  and  b 
c,  the  lateral  margins  of  the  lower  aeroplane 
are  indicated,  respectively,  by  the  lines  e  h 
and  f  g,  while  the  rear  margins  of  the  upper 
and  lower  areoplanes  are  indicated,  respec- 
tively, by  the  lines  c  d  and  g  h. 

Before  proceeding  to  a  description  of  the 
fundamental  theory  of  operation  of  the  struc- 
ture we  will  first  describe  the  preferred  mode 
of  constructing  the  aeroplanes  and  those  por- 
tions of  the  structure  which  serve  to  connect 
the  two  aeroplanes. 

Each  aeroplane  is  formed  by  stretching 
cloth  or  other  suitable  fabric  over  a  frame 
compoped  of  two  parallel  transverse  spars  3, 
extending  from  side  to  side  of  the  machine, 
their  ends  being  connected  by  bows  4,  ex- 
tending from  front  to  rear  of  the  machine. 
The  front  and  rear  spars  3  of  each  aeroplane 
are  connected  by  a  series  of  parallel  ribs  3. 
which  preferably  extend  somewhat  beyond 
the  rear  spar,  as  shown.  These  spars,  bows. 
and  ribs  are  preferably  constructed  of  wood 
having  the  necessary  strength,  combined 
with  lightness  and  flexibility.  Upon  this 
framework  the  cloth  which  forms  the  sup- 
porting-surface of  the  aeroplane  Is  secured, 


452 


VEHICLES  OF  THE  AIR 


the  frame  being  inclosed  in  the  cloth.  The 
cloth  for  each  aeroplane  previously  to  its  at- 
tachment to  its  frame  is  cut  on  the  bias  and 
made  up  into  a  single  piece  approximately 
the  size  and  shape  of  the  aeroplane,  having 
the  threads  of  the  fabric  arranged  diagonally 
to  the  transverse  spars  and  longitudinal  ribs, 
as  indicated  at  6  in  Fig.  2.  Thus  the  diag- 
onal threads  of  the  cloth  form  truss  systems 
with  the  spars  and  ribs,  the  threads  consti- 
tuting the  diagonal  members.  A  hem  is 
formed  at  the  rear  edge  of  the  cloth  to  receive 
a  wire  7,  which  is  connected  to  the  ends  of 
the  rear  spar  and  supported  by  the  rear- 
wardly-extending  ends  of  the  longitudinal 
ribs  5,  thus  forming  a  rearwardly-extending 
flap  or  portion  of  the  aeroplane.  This  con- 
struction of  the  aeroplanes  gives  a  surface 
which  has  very  great  strength  to  withstand 
lateral  and  longitudinal  strains,  at  the  same 
time  being  capable  of  being  bent  or  twisted 
in  the  manner  hereinafter  described. 

When  two  aeroplanes  are  employed,  as  In 
the  construction  illustrated,  they  are  con- 
nected together  by  upright  standards  8. 
These  standards  are  substantially  rigid,  be- 
ing preferably  constructed  of  wood  and  of 
equal  length,  equally  spaced  along  the  front 
and  rear  edges  of  the  aeroplane,  to  which 
they  are  connected  at  their  top  and  bottom 
ends  by  hinged  joints  or  universal  joints  of 
any  suitable  description.  We  have  shown 
one  form  of  connection  which  may  be  used 
for  this  purpose  in  Figs.  4  and  5  of  the  draw- 
ings. In  this  construction  each  end  of  the 
standard  8  has  secured  to  it  an  eye  9,  which 
engages  with  a  hook  10,  secured  to  a  bracket- 
plate  11,  which  latter  plate  is  in  turn  fas- 
tened to  the  spar  3.  Diagonal  braces  or  stay 
wires  12  extend  from  each  end  of  each  stand- 
ard to  the  opposite  ends  of  the  adjacent 
standards,  and  as  a  convenient  mode  of  at- 
taching these  parts  I  have  shown  a  hook  13 
made  integral  with  the  hook  10  to  receive 
the  end  of  one  of  the  stay -wires,  the  other 
stay-wire  being  mounted  on  the  hook  10. 
The  hook  13  is  shown  as  bent  down  to  retain 
the  stay-wire  in  connection  to  it,  while  the 
hook  10  is  shown  as  provided  with  a  pin  14 
to  hold  the  stay -wire  12  and  eye  9  in  position 
thereon.  It  will  be  seen  that  this  construc- 
tion forms  a  truss  system  which  gives  the 
whole  machine  great  transverse  rigidity  and 
strength,  while  at  the  same  time  the  jointed 
connections  of  the  parts  permit  the  aero- 
planes to  be  bent  or  twisted  in  the  manner 
which  we  will  now  proceed  to  describe. 

15  indicates  a  rope  or  other  flexible  con- 
nection extending  lengthwise  of  the  front  of 
the  machine  above  the  lower  aeroplane,  pass- 
ing under  pulleys  or  other  suitable  guides  16 
at  the  front  corners  e  and  £  of  the  lower  aero- 
plane, and  extending  thence  upward  and 
rearward  to  the  upper  rear  corners  o  and  d 
of  the  upper  aeroplane,  where  they  are  at- 
tached, as  indicated  at  17.  To  the  central 
portion  of  this  rope  there  is  connected  a  lat- 
erally-movable cradle  18,  which  forms  a 
means  for  moving  the  rope  lengthwise  in  one 
direction  or  the  other,  the  cradle  being  mov- 
able toward  either  side  of  the  machine.  We 
have  devised  this  cradle  as  a  convenient 
means  for  operating  the  rope  15,  and  the 
machine  is  intended  to  be  generally  used  with 
the  operator  lying  face  downward  on  the 
lower  aeroplane,  with  his  head  to  the  front, 
so  that  the  operator's  body  rests  on  the  cra- 
dle, and  the  cradle  can  be  moved  laterally  by 
the  movements  of  the  operator's  body.  It 
will  be  understood,  however,  that  the  rope  15 
may  be  manipulated  in  any  suitable  manner. 

19  indicates  a  second  rope  extending  trans- 
versely of  the  machine  along  the  rear  edge  of 
the  body  portion  of  the  lower  aeroplane,  pass- 
ing under  suitable  pulleys  or  guides  20  at  the 
rear  corners  g  and  h  of  the  lower  aeroplane 
and  extending  thence  diagonally  upward  to 


the  front  corners  a  and  b  of  the  upper  aero- 
plane, where  its  ends  are  secured  in  any  suit- 
able manner,  as  indicated  at  21. 

Considering  the  structure  so  far  as  we  have 
now  described  it  and  assuming  that  the 
cradle  18  be  moved  to  the  right  in  Figs.  1  and 
2,  as  indicated  by  the  arrows  applied  to  the 
cradle  in  Fig.  1  and  by  the  dotted  lines  in 
Fig.  2,  it  will  be  seen  that  that  portion  of  the 
rope  15  passing  under  the  guide-pulley  at  the 
corner  e  and  secured  to  the  corner  d  will  be 
under  tension,  while  slack  is  paid  out 
throughout  the  other  side  or  half  of  the  rope 
15.  The  part  of  the  rope  15  under  tension 
exercises  a  downward  pull  upon  the  rear  up- 
per corner  d  of  the  structure  and  an  upward 
pull  upon  the  front  lower  corner  e,  as  indi- 
cated by  the  arrows.  This  causes  the  corner 
d  to  move  downward  and  the  corner  e  to  move 
upward.  As  the  corner  e  moves  upward  it 
carries  the  corner  a  upward  with  it,  since  the 
intermediate  standard  8  is  substantially  rigid 
and  maintains  an  equal  distance  between  the 
corners  a  and  e  at  all  times.  Similarly,  the 
standard  8,  connecting  the  corners  d  and  h, 
causes  the  corner  h  to  move  downward  in  uni- 
son with  the  corner  d,  Since  the  corner  a 
thus  moves  upward  and  the  corner  h  moves 
downward,  that  portion  of  the  rope  19  con- 
nected to  the  corner  a  will  be  pulled  upward 
through  the  pulley  20  at  the  corner  h,  and  the 
pull  thus  exerted  on  the  rope  19  will  pull  the 
corner  b  on  the  other  side  of  the  machine 
downward  and  at  the  same  time  pull  the  cor- 
ner g  at  said  other  side  of  the  machine  up- 
ward. This  results  in  a  downward  movement 
of  the  corner  b  and  an  upward  movement  of 
the  corner  o.  Thus  it  results  from  a  lateral 
movement  of  the  cradle  18  to  the  right  in 
Fig.  1  that  the  lateral  margins  a  d  and  e  h  at 
one  side  of  the  machine  are  moved  from  their 
normal  positions,  in  which  they  lie  in  the  nor- 
mal planes  of  their  respective  aeroplanes,  into 
angular  relations  with  said  normal  planes, 
each  lateral  margin  on  this  side  of  the  ma- 
chine being  raised  above  said  normal  plane  at 
its  forward  end  and  depressed  below  said  nor- 
mal plane  at  its  rear  end,  said  lateral  margins 
being  thus  inclined  upward  and  forward.  At 
the  same  time  a  reverse  inclination  is  impart- 
ed to  the  lateral  margins  b  o  and  f  g  at  the 
other  side  of  the  machine,  their  inclination 
being  downward  and  forward.  These  posi- 
tions are  indicated  in  dotted  lines  in  Fig.  1  of 
the  drawings.  A  movement  of  the  cradle  18 
in  the  opposite  direction  from  its  normal  po- 
sition will  reverse  the  angular  inclination  of 
the  lateral  margins  of  the  aeroplanes  in  an 
obvious  manner.  By  reason  of  this  con- 
struction it  will  be  seen  that  with  the  particu- 
lar mode  of  construction  now  under  consider- 
ation it  is  possible  to  move  the  forward  corner 
of  the  lateral  edges  of  the  aeroplane  on  one 
side  of  the  machine  either  above  or  below  the 
normal  planes  of  the  aeroplanes,  a  reverse 
movement  of  the  forward  corners  of  the  lat- 
eral margins  on  the  other  side  of  the  machine 
occurring  simultaneously.  During  this  op- 
eration each  aeroplane  is  twisted  or  distorted 
around  a  line  extending  centrally  across  the 
same  from  the  middle  of  one  lateral  margin  to 
the  middle  of  the  other  lateral  margin,  the 
twist  due  to  the  moving  of  the  lateral  mar- 
gins to  different  angles  extending  across  each 
aeroplane  from  side  to  side,  so  that  each  aero- 
plane-surface is  given  a  helicoidal  warp  or 
twist.  We  prefer  this  construction  and 
mode  of  operation  for  the  reason  that  it  gives 
a  gradually-increasing  angle  to  the  body  of 
each  aeroplane  from  the  central  longitudinal 
line  thereof  outward  to  the  margin,  thus  giv- 
ing a  continuous  surface  on  each  side  of  the 
machine,  which  has  a  gradually  increasing  or 
decreasing  angle  of  incidence  from  the  center 
of  the  machine  to  either  side.  We  wish  it  to 
be  understood,  however,  that  our  invention  is 
not  limited  to  this  particular  construction, 


Count  de  Lambert  in  Wright  Biplane  at  Juvisy,  France. 


FIGURE  254. — View  down  main  hall  of  Paris  Aeronautical  Salon,  which  closed  October  15, 
1009.  The  value  of  the  exhibits  and  accessories,  the  cost  of  the  decorations,  and  the 
attendance  was  far  greater  than  at  any  automobile  show  ever  given  in  the  United  States 
or  Europe.  It  was  the  second  annual  event  of  the  kind  to  be  held  in  Paris  and  a  large 
number  of  orders  for  various  makes  of  machines  was  placed  for  future  delivery — 110  being 
for  one  well-known  monoplane. 


FIGURE  259.— Wright  Patent  Drawings. 


454 


VEHICLES  OF  THE  AIR 


since  any  construction  whereby  the  angular 
relations  of  the  lateral  margins  of  the  aero- 
planes may  be  varied  in  opposite  directions 
with  respect  to  the  normal  planes  of  said 
aeroplanes  comes  within  the  scope  of  our  in- 
vention. Furthermore,  it  should  be  under- 
stood that  while  the  lateral  margins  of  the 
aeroplanes  move  to  different  angular  posi- 
tions with  respect  to  or  above  and  below  the 
normal  planes  of  said  aeroplanes  it  does  not 
necessarily  follow  that  these  movements 
bring  the  opposite  lateral  edges  to  different 
angles  respectively  above  and  below  a  hori- 
zontal plane,  since  the  normal  planes  of  the 
bodies  of  the  aeroplanes  are  inclined  to  the 
horizontal  when  the  machine  is  in  flight,  said 
inclination  being  downward  from  front  to  rear, 
and  while  the  forward  corners  on  one  side  of 
the  machine  may  be  depressed  below  the  nor- 
mal planes  of  the  bodies  of  the  aeroplanes 
said  depression  is  not  necessarily  sufficient  to 
carry  them  below  the  horizontal  planes  pass- 
ing through  the  rear  corners  on  that  side. 
Moreover,  although  we  prefer  to  so  construct 
the  apparatus  that  the  movements  of  the  lat- 
eral margins  on  the  opposite  sides  of  the  ma- 
chine are  equal  in  extent  and  opposite  in  di- 
rection, yet  our  invention  is  not  limited  to  a 
construction  producing  this  result,  since  it 
may  be  desirable  under  certain  circumstances 
to  move  the  lateral  margins  on  one  side  of  the 
machine  in  the  manner  Just  described  with- 
out moving  the  lateral  margins  on  the  other 
side  of  the  machine  to  an  equal  extent  in  the 
opposite  direction.  Turning  now  to  the  pur- 
pose of  this  provision  for  moving  the  lateral 
margins  of  the  aeroplanes  in  the  manner  de- 
scribed, it  should  be  premised  that  owing  to 
various  conditions  of  wind-pressure  and  other 
causes  the  body  of  the  machine  is  apt  to  be- 
come unbalanced  laterally,  one  side  tending 
to  sink  and  the  other  side  tending  to  rise,  the 
machine  turning  around  Its  central  longitu- 
dinal axis.  The  provision  which  we  hare 
just  described  enables  the  operator  to  meet 
this  difficulty  and  preserve  the  lateral  bal- 
ance of  the  machine.  Assuming  that  for 
come  cause  that  side  of  the  machine  which 
lies  to  the  left  of  the  observer  in  Figs.  1  and  2 
has  shown  a  tendency  to  drop  downward,  a 
movement  of  the  cradle  18  to  the  right  of  said 
figures,  as  hereinbefore  assumed,  will  move 
the  lateral  margins  of  the  aeroplanes  in  the 
manner  already  described,  so  that  the  mar- 
gins a  d  and  e  h  will  be  inclined  downward 
and  rearward  and  the  lateral  margins  b  o  and 
f  g  will  be  inclined  upward  and  rearward  with 
respect  to  the  normal  planes  of  the  bodies  of  the 
aeroplanes.  With  the  parts  of  the  machine 
in  this  position  it  will  be  seen  that  the  lateral 
margins  a  d  and  e  h  present  a  larger  angle  of 
incidence  to  the  resisting  air,  while  the  lat- 
eral margins  on  the  other  side  of  the  machine 
present  a  smaller  angle  of  incidence.  Owing 
to  this  fact,  the  side  of  the  machine  present- 
ing the  larger  angle  of  incidence  will  tend  to 
lift  or  move  upward,  and  this  upward  move- 
ment will  restore  the  lateral  balance  of  the 
machine.  When  the  other  side  of  the  ma- 
chine tends  to  drop,  a  movement  of  the  cradle 
18  in  the  reverse  direction  will  restore  the 
machine  to  its  normal  lateral  equilibrium. 
Of  course  the  same  effect  will  be  produced  in 
the  same  way  in  the  case  of  a  machine  employ- 
ing only  a  single  aeroplane. 

In  connection  with  the  body  of  the  ma- 
chine as  thus  operated  we  employ  a  vertical 
rudder  or  tail  22,  so  supported  as  to  turn 
around  a  vertical  axis.  This  rudder  is  sup- 
ported at  the  rear  ends  of  supports  or  arms 
23,  pivoted  at  their  forward  ends  to  the  rear 
margins  of  the  upper  and  lower  aeroplanes, 
respectively.  These  supports  are  preferably 
V-shaped,  as  shown,  so  that  their  forward 
•nds  are  comparatively  widely  separated, 
their  pivots  being  Indicated  at  24.  Said  sup- 
ports are  free  to  swing  upward  at  their  free 


rear  ends,  as  indicated  in  dotted  lines  in  Fig. 
3,  their  downward  movement  being  limited 
in  any  suitable  manner.  The  vertical  pivots 
of  the  rudder  22  are  indicated  at  25,  and  one 
of  these  pivots  has  mounted  thereon  a  sheave 
or  pulley  26,  around  which  passes  a  tiller- 
rope  27,  the  ends  of  which  are  extended  out 
laterally  and  secured  to  the  rope  19  on  oppo- 
site sides  of  the  central  point  of  said  rope. 
By  reason  of  this  construction  the  lateral 
shifting  of  the  cradle  18  serves  to  turn  the 
rudder  to  one  side  or  the  other  of  the  line  of 
flight.  It  will  be  observed  in  this  connection 
that  the  construction  is  such  that  the  rudder 
will  always  be  so  turned  as  to  present  its  re- 
sisting-surface  on  that  side  of  the  machine  on 
which  the  lateral  margins  of  the  aeroplanes 
present  the  least  angle  of  resistance.  The 
reason  of  this  construction  is  that  when  the 
lateral  margins  of  the  aeroplanes  are  so  turned 
in  the  manner  hereinbefore  described  as  to 
present  different  angles  of  incidence  to  the 
atmosphere  that  side  presenting  the  largest 
angle  of  incidence,  although  being  lifted  or 
moved  upward  in  the  manner  already  de- 
scribed, at  the  same  time  meets  with  an  in- 
creased resistance  to  its  forward  motion,  and 
is  therefore  retarded  in  its  forward  motion, 
while  at  the  same  time  the  other  side  of  the 
machine,  presenting  a  smaller  angle  of  inci- 
dence, meets  with  less  resistance  to  its  for- 
ward motion  and  tends  to  move  forward  more 
rapidly  than  the  retarded  side.  This  gives 
the  machine  a  tendency  to  turn  around  its 
vertical  axis,  and  this  tendency  if  not  prop- 
erly met  will  not  only  change  the  direction  of 
the  front  of  the  machine,  but  will  ultimately 
permit  one  side  thereof  to  drop  into  a  posi- 
tion vertically  below  the  other  side  with  the 
aeroplanes  in  vertical  position,  thus  causing 
the  machine  to  fall.  The  movement  of  the 
rudder  hereinbefore  described  prevents  this 
action,  since  it  exerts  a  retarding  intiuence  on 
that  side  of  the  machine  which  tends  to  move 
forward  too  rapidly  and  keeps  the  machine 
with  its  front  properly  presented  to  the  direc- 
tion of  flight  and  with  its  body  properly  bal- 
anced around  its  central  longitudinal  axis. 
The  pivoting  of  the  supports  23  so  as  to  per- 
mit them  to  swing  upward  prevents  injury  to 
the  rudder  and  its  supports  in  case  the  ma- 
chine alights  at  such  an  angle  as  to  cause  the 
rudder  to  strike  the  ground  first,  the  parts 
yielding  upward,  as  indicated  in  dotted  lines 
In  Fig.  3,  and  thus  preventing  injury  or 
breakage.  We  wish  it  to  be  understood, 
however,  that  we  do  not  limit  ourselves  to 
the  particular  description  of  rudder  set  forth, 
the  essential  being  that  the  rudder  shall  be 
vertical  and  shall  be  so  moved  as  to  pre- 
sent its  resisting  surface  on  that  side  of  the 
machine  which  offers  the  least  resistance  to 
the  atmosphere,  so  as  to  counteract  the  tend- 
ency of  the  machine  to  turn  around  a  vertical 
axis  when  the  two  sides  thereof  offer  different 
resistances  to  the  air. 

From  the  central  portion  of  the  front  of  the 
machine  struts  28  extend  horiontaily  for- 
ward from  the  lower  aeroplane,  and  struts  29 
extend  downward  and  forward  from  the  cen- 
tral portion  of  the  upper  aeroplane,  their 
front  ends  being  united  to  the  struts  28,  the 
forward  extremities  of  which  are  turned  up, 
as  indicated  at  30.  These  struts  28  and  29 
form  truss-skids  projecting  in  front  of  the 
whole  frame  of  the  machine  and  serving  to 
prevent  the  machine  from  rolling  over  for- 
ward when  it  alights.  The  struts  29  serve  to 
brace  the  upper  portion  of  the  main  frame 
and  resist  its  tendency  to  move  forward 
after  the  lower  aeroplane  has  been  stopped 
by  its  contact  with  the  earth,  thereby  reliev- 
ing the  rope  19  from  undue  strain,  for  it  will  be 
understood  that  when  the  machine  comes 
into  contact  with,  the  earth  further  forward 
movement  of  the  lower  portion  thereof  being 
suddenly  arrested  the  inertia  of  the  upper 


MISCELLANY 


455 


portion  would  tend  to  cause  It  to  continue  to 
move  forward  If  not  prevented  by  the  struts 
29.  and  this  forward  movement  of  the  upper 
portion  would  bring  a  very  violent  strain 
upon  the  rope  19,  since  It  Is  fastened  to  the 
upper  portion  at  both  of  its  ends,  while  its 
lower  portion  is  connected  by  the  guides  20 
to  the  lower  portion.  The  struts  28  and  29 
also  serve  to  support  the  front  or  horizontal 
rudder,  the  construction  of  which  we  will 
now  proceed  to  describe. 

The  front  rudder  31  Is  a  horizontal  rudder 
having  a  flexible  body,  the  same  consisting  of 
three  stiff  cross-pieces  or  sticks  32,  33,  and  34, 
and  the  flexible  ribs  35,  connecting  said  cross- 
pieces  and  extending  from  front  to  rear.  The 
frame  thus  provided  Is  covered  by  a  suitable 
fabric  stretched  over  the  same  to  form  the 
body  of  the  rudder.  The  rudder  is  supported 
from  the  struts  29  by  means  of  the  interme 
diate  cross-piece  32,  which  is  located  near  the 
center  of  pressure  slightly  in  front  of  a  line 
equidistant  between  the  front  and  rear  edges 
of  the  rudder,  the  cross-piece  32  forming  the 
pivotal  axis  of  the  rudder,  so  as  to  constitute 
a  balanced  rudder.  To  the  front  edge  of  the 
rudder  there  are  connected  springs  36,  which 
springs  are  connected  to  the  upturned  ends 
30  of  the  struts  28,  the  construction  being 
such  that  said  springs  tend  to  resist  any 
movement  either  upward  or  downward  of  the 
front  edge  of  the  horizontal  rudder.  The 
rear  edge  of  the  rudder  lies  Immediately  In 
front  of  the  operator  and  may  be  operated  by 
him  in  any  suitable  manner.  We  have 
shown  a  mechanism  for  this  purpose  com- 
prising a  roller  or  shaft  37,  which  may  be 
grasped  by  the  operator  so  as  to  turn  the 
same  in  either  direction.  Bands  38  extend 
from  the  roller  37  forward  to  and  around  a 
similar  roller  or  shaft  39,  both  rollers  or  shafts 
being  supported  in  suitable  bearings  on  the 
struts  28.  The  forward  roller  or  shaft  has 
rearwardly-extending  arms  40,  which  are 
connected  by  links  41  with  the  rear  edge  of 
the  rudder  31.  The  normal  position  of  the 
rudder  31  is  neutral  or  substantially  parallel 
with  the  aeroplanes  1  and  2;  but  its  rear 
edge  may  be  moved  upward  or  downward,  so 
as  to  be  above  or  below  the  normal  plane  of 
said  rudder  through  the  mechanism  provided 
for  that  purpose.  It  will  be  seen  that  the 
springs  36  will  resist  any  tendency  of  the  for- 
ward edge  of  the  rudder  to  move  in  either  di- 
rection, so  that  when  force  is  applied  to  the 
rear  edge  of  said  rudder  the  longitudinal  ribs 
35  beud,  and  the  rudder  thus  presents  a  con- 
cave surface  to  the  action  of  the  wind  either 
above  or  below  its  normal  plane,  said  surface 
presenting  a  small  angle  of  incidence  at  its 
forward  portion  and  said  angle  of  incidence 
rapidly  Increasing  toward  the  rear.  This 
greatly  increases  the  efficiency  of  the  rudder 
as  compared  with  a  plane  surface  of  equal 
area.  By  regulating  the  pressure  on  the  up- 
per and  lower  sides  of  the  rudder  through 
changes  of  angle  and  curvature  in  the  man- 
ner described  a  turning  movement  of  the 
main  structure  around  Its  transverse  axis 
may  be  effected,  and  the  course  of  the  machine 
may  thus  be  directed  upward  or  downward 
at  the  will  of  the  operator  and  the  longitudi- 
nal balance  thereof  maintained. 

Contrary  to  the  usual  custom,  we  place  the 
horizontal  rudder  in  front  of  the  aeroplanes 
at  a  negative  angle  and  employ  no  horizontal 
tail  at  all.  By  this  arrangement  we  obtain  a 
forward  surface  which  is  almost  entirely  free 
from  pressure  under  ordinary  conditions  of 
flight,  but  which  even  if  not  moved  at  all 
from  its  original  position  becomes  an  effl- 
cient  lifting-surface  whenever  the  speed  of 
the  machine  is  accidentally  reduced  very 
much  below  the  normal,  and  thus  largely 
counteracts  that  backward  travel  of  the  cen- 
ter of  pressure  on  the  aeroplanes  which  has 
frequently  been  productive  of  serious  injuries 


by  causing  the  machine  to  turn  downward 
and  forward  and  strike  the  ground  head-on. 
We  are  aware  that  a  forward  horizontal  rud- 
der of  different  construction  has  been  used  in 
combination  with  a  supporting-surface  and  a 
rear  horizontal  rudder;  but  this  combination 
was  not  Intended  to  effect  and  does  not  effect 
the  object  which  we  obtain  by  the  arrange- 
ment hereinbefore  described. 

We  have  used  the  term  "aeroplane"  in  this 
specification  and  the  appended  claims  to  In- 
dicate the  supporting-surface  or  supporting- 
surfaces  by  means  of  which  the  machine  is 
sustained  in  the  air,  and  by  this  term  we  wish, 
to  be  understood  as  including  any  suitable 
supporting-surface  which  normally  is  sub- 
stantially flat,  although  of  course  when  con- 
structed of  cloth  or  other  flexible  fabric,  as 
we  prefer  to  construct  them,  these  surfaces 
may  receive  more  or  less  curvature  from  the 
resistance  of  the  air,  as  indicated  in  Fig.  3. 

We  do  not  wish  to  be  understood  as  limit- 
Ing  ourselves  strictly  to  the  precise  details  of 
construction  hereinbefore  described  and 
shown  in  the  accompanying  drawings,  as  it 
is  obvious  that  these  details  may  be  modified 
without  departing  from  the  principles  of  our 
Invention.  For  instance,  while  we  prefer  the 
construction  illustrated  in  which  each  aero- 
plane is  given  a  twist  along  its  entire  length 
in  order  to  set  its  opposite  lateral  margins  at 
different  angles  we  have  already  pointed  out 
that  our  invention  is  not  limited  to  this  form 
of  construction,  since  it  is  only  necessary  to 
move  the  lateral  marginal  portions,  and  where 
these  portions  alone  are  moved  only  those 
upright  standards  which  support  the  mov- 
able portion  require  flexible  connections  at 
their  ends. 

Having  thus  fully  described  our  invention, 
what  we  claim  as  new,  and  desire  to  secure 
by  Letters  Patent,  is— 

1.  In    a    flying-machine,     a    normally    flat 
aeroplane     having    lateral     marginal     portions 
capable    of    movement    to    different    positions 
above  or  below  the  normal  plane  of  the  body 
of  the  aeroplane,  such   movement  being  about 
an  axis  transverse  to  the  line  of  flight,  where- 
by   said    lateral    marginal    portions    may    be 
moved    to    different    angles    relatively    to    the 
normal  plane  of  the  body  of  the  aeroplane,  so 
as    to    present     to    the    atmosphere    different 
angles  of   incidence,    and    means   for   so   mov- 
ing   said    lateral    marginal    portions,    substan- 
tially as  described. 

2.  In    a    flying-machine,    the    combination, 
with    two    normally    parallel    aeroplanes,     su- 
perposed the  one   above   the  other,   of   upright 
standards     connecting     said     planes     at     their 
margins,    the    connections    between    the    stand- 
ards and  aeroplanes  at  the  lateral  portions  of 
the    aeroplanes    being    by    means    of    flexible 
Joints,   each  of  said  aeroplanes  having  lateral 
marginal     portions    capable    of    movement     to 
different  positions  above  or  below  the  normal 
plane  of  the  body  of  the  aeroplane,  such  move- 
ment   boiDi?    about   an   axis    transverse    to   the 
line   of   flight,    whereby   said   lateral   marginal 
portions    may    be    moved    to    different    angles 
relatively  to  the  normal  plane  of  the  body  of 
the  aeroplane,   so  as  to  present  to  the   atmos- 
phere different  angles  of  incidence,   the  stand- 
ards   maintaining    a     fixed     distance     between 
the  portions  of  the  aeroplanes  which  they  con- 
nect,   and    means    for    imparting    such    move- 
ment  to  the  lateral   marginal  portions  of  the 
aeroplanes,    substantially    as   described. 

3.  In     a     flying-machine,     a     normally    flat 
aeroplane     having     lateral     marginal     portions 
capable    of    movement    to     different    positions 
above  or  below   the  normal  plane  of  the  body 
of  the  aeroplane,   such  movement  being  about 
an  axis  transverse  to  the  line  of  flight,  where- 
by   said    lateral    marginal    portions    may    be 
moved    to    different    angles    relatively    to    the 
normal    plane   of    the   body   of    the   aeroplane, 
and  also  to  different  angles  relatively  to  each 


456 


VEHICLES  OF  THE  AIR 


other,  so  as  to  present  to  the  atmosphere  dif- 
ferent angles  of  incidence,  and  means  for  si- 
multaneously imparting  such  movement  to 
said  lateral  marginal  portions,  substantially 
as  described. 

4.  In    a    flying-machine,    the    combination, 
with     parallel     superposed     aeroplanes,      each 
having    lateral    marginal    portions    capable    of 
movement    to  different    positions   above   or   be- 
low the  normal  plane  of  the  body  of  the  aero- 
plane,   such    movement    being    about    an    axis 
transverse   to  the  line  of  flight,   whereby  said 
lateral    marginal    portions    may    be    moved    to 
different  angles  relatively  to  the  normal  plane 
of  the  body  of  the  aeroplane,   and  to  different 
angles  relatively  to  each  other,    so  as  to  pre- 
sent to  the  atmosphere  different  angles  of  in- 
cidence,    of     uprights     connecting     said    aero- 
planes at  their  edges,  the  uprights  connecting 
the    lateral    portions   of    the    aeroplanes    being 
connected     with     said    aeroplanes     by     flexible 
joints,    and  means   for  simultaneously   impart- 
ing   such    movement    to   said   lateral   marginal 
portions,    the    standards    maintaining    a    fixed 
distance   between    the    parts   which    they    con- 
nect,    whereby    the    lateral    portions    on    the 
same    side  of   the    machine   are   moved   to  the 
same  angle,   substantially  as  described. 

5.  In    a    flying  machine,    an    aeroplane   bar- 
ing substantially  the  form  of  a  normally  flat 
rectangle    elongated    transversely    to    the    line 
of   flight,   in  combination   with   means   for  im- 
parting  to   the    lateral    margins   of    said   aero- 
plane a  movement  about  an  axis  lying  in  the 
body    of    the    aeroplane    perpendicular    to    said 
lateral  margins,   and  thereby  moving  said  lat- 
eral   margins    into    different    angular    relations 
to  the  normal  plane  of  the  body  of  the  aero- 
plane,  substantially  as  described. 

6.  In    a    flying-machine,     the    combination, 
with    two    superposed    and    normally    parallel 
aeroplanes,     each     having     substantially      the 
form   of   a   normally    flat   rectangle    elongated 
transversely   to  the   line   of   flight,    of   upright 
standards   connecting   the   edges   of   said    aero- 
planes   to    maintain    their    equidistance.    those 
standards  at  the  lateral  portions  of  said  aero- 
planes   being    connected   therewith    by    flexible 
joints,    and   means  for   simultaneously  impart- 
ing to  both  lateral  margins  or  both  aeroplanes 
a   movement  about   axes   which   are  perpendic- 
ular to  said  margins  and  in  the  planes  of  the 
bodies     of     the     respective     aeroplanes,     and 
thereby    moving    the    lateral    margins    on    the 
opposite    sides    of    the    machine    into    different 
angular  relations  to  the  normal  planes  of  the 
respective     aeroplanes,     the     margins     on     the 
same  side  of  the  machine  moving  to  the  same 
angle,  and  the  margins  on  one  side  of  the  ma- 
chine moving   to   an    angle   different  from    the 
angle  to  which  the  margins  on  the  other  side 
of    the    machine    move,    substantially    as    de- 
scribed. 

7.  In    a    flying-machine,     the    combination, 
with   an   aeroplane,    and   means   for  simultane- 
ously moving  the  lateral  portions  thereof  into 
different     angular     relations     to     the     normal 
plane   of    the   body    of    the    aeroplane    and    to 
each  other,  so  as  to  present  to  the  atmosphere 
different    angles    of    incidence,    of    a    vertical 
rudder,    and    means    whereby    said    rudder    is 
caused  to  present  to  the  wind  that  side  there- 
of   nearest    the    side   of   the    aeroplane    having 
the  smaller  angle  of  incidence  and  offering  the 
least    resistance    to    the    atmosphere,    substan- 
tially as  described. 

8.  In    a    flying-machine,     the    combination, 
with    two    superposed    and    normally    parallel 
aeroplanes,    upright    standards    connecting    the 
edges    of    said    aeroplanes    to    maintain    their 
equidistance,    those    standards    at    the    lateral 
portions    of    said    aeroplanes    being    connected 
therewith  by  flexible  Joints,  and  means  for  si- 
multaneously    moving     both     lateral     portions 
of   both   aeroplanes    into   different    angular   re- 
lations to  the  normal  planes  of  the  bodies  of 
the    respective    aeroplanes,     the    lateral    por- 


tions on  one  side  of  the  machine  being  moved 
to  an  angle  different  from  that  to  which  the 
lateral  portions  on  the  other  side  of  the  ma 
chine  are  moved,  so  as  to  present  different 
angles  of  incidence  at  the  two  sides  of  the  ma 
chine,  of  a  vertical  rudder,  and  means  where- 
by said  rudder  is  caused  to  present  to  the 
wind  that  side  thereof  nearest  the  side  of  the 
aeroplanes  having  the  smaller  angle  of  inci- 
dence and  offering  the  least  resistance  to  the 
atmosphere,  substantially  as  described. 

9.  In    a    flying-machine,    an    aeroplane    nor- 
mally   flat    and  elongated    transversely    to   the 
line  of  flight,    in  combination  with   means  for 
imparting  to  said  aeroplane  a  helicoidal  warp 
around  an  axis  transverse  to  the  line  of  flight 
and  extending  centrally  along  the  body  of  the 
aeroplane    in    the    direction    of    the    elongation 
of    the    aeroplane,    substantially    as    described. 

10.  In    a     flying-machine,     two     aeroplanes, 
each     normally     flat      and     elongated     trans- 
versely   to    the    line    of    flight,     and    upright 
standards   connecting   the   edges   of   said   aero- 
planes    to     maintain     their    equidistance,     the 
connections   between   said   standards  and   aero- 
planes   being    by    means   of   flexible    joints,    in 
combination    with     means    for     simultaneously 
imparting   to  each    of    said   aeroplanes   a    heli- 
coidal warp  around  an  axis  transverse  to  the 
line    of    flight    and    extending    centrally    along 
the  body  of  the  aeroplane  in  the  direction  of 
the  elongation  of  the  aeroplane,   substantially 
as  described. 

11.  In    a    flying-machine,    two    aeroplanes, 
each     normally      flat      and     elongated      trans- 
versely   to    the    line    of    flight,     and    upright 
standards   connecting   the   edges   of    said   aero- 
planes   to    maintain    their     equidistance,     the 
connections      between      such      standards      and 
aeroplanes   being    by    means  of   flexible   joints, 
in    combination     with     means     for     simultane- 
ously imparting   to  each  of   said  aeroplanes   a 
helicoidal  warp    around   an  axis   transverse   to 
the     line    of    flight    and    extending    centrally 
along  the  body  of  the  aeroplane  in  the  direc- 
tion of  the  elongation  of  the  aeroplane,  a  ver- 
tical rudder,    and   means  whereby   said  rudder 
is    caused    to    present    to    the    wind    that    side 
thereof    nearest    the    side    of    the    aeroplanes 
having  the  smaller  angle  of  incidence  and  of- 
fering the  least  resistance   to  the  atmosphere, 
substantially  as  described. 

12.  In    a    flying-machine,    the    combination, 
with  an  aeroplane,  of  a  normally  flat  and  sub- 
stantially     horizontal      flexible      rudder,      and 
means    for    curving     said    rudder     rearwardly 
and      upwardly     or      rearwardly      and      down- 
wardly with  respect  to  its  normal  plane,  sub- 
stantially as  described. 

13.  In    a    flying-machine,    the    combination, 
with  an  aeroplane,  of  a  normally  flat  and  sub- 
stantially   horizontal    flexible    rudder    pivotally 
mounted  on  an  axis  transverse  to  the  line  of 
flight  near  its  center,    springs  resisting  verti- 
cal movement  of  the  front  edge  of  said  rudder, 
and   means   for   moving  the  rear   edge   of  said 
rudder     above     or     below     the     normal     plane 
thereof,  substantially  as  described. 

14.  A      flying-machine      comprising      super- 
posed   connected    aeroplanes,    means    for    mov- 
ing the  opposite  lateral   portions  of  said  aero- 
planes    to     different     angles     to     the     normal 
planes    thereof,    a    vertical    rudder,    means    for 
mov'^c  said   vertical   rudder   toward   that  side 
of       *   machine   presenting    the    smaller   angle 
of    lucidence    and    the    least    resistance    to   the 
atmosphere,     and     a     horizontal     rudder     pro- 
vided with  means  for  presenting   its   upper  or 
under  surface  to  the  resistance  of  the  atmos- 
phere,  substantially  as  described. 

15.  A      flying-machine      comprising      super- 
posed   connected    aeroplanes,    means    for    mov- 
ing the  opposite  lateral  portions  of  said  aero- 
planes    to     different     angles     to     the     normal 
planes    thereof,    a    vertical    rudder,    means   for 
moving   said   vertical  rudder  toward   that  side 
of   the   machine   presenting   the  smaller   angle 


MISCELLANY 


457 


of  incidence  and  the  least  resistance  to  the  at- 
mosphere, and  a  horizontal  rudder  provided 
with  means  for  presenting  its  upper  or  under 
surface  to  the  resistance  of  the  atmosphere, 
said  vertical  rudder  being  located  at  the  rear 
of  the  machine  and  said  horizontal  rudder  at 
the  front  of  the  machine,  substantially  as  de- 
scribed. 

16.  In    a    flying-machine,    the    combination, 
with     two     superposed     and     connected     aero- 
planes,   of    an    arm    extending    rearward    from 
each   aeroplane,    said   arms   being   parallel   and 
free  to  swing  upward  at  their  rear  ends,  and  a 
vertical   rudder  pivotally   mounted  in   the  rear 
ends  of  said  arms,   substantially  as  described. 

17.  A    flying-machine    comprising    two    su- 
perposed   aeroplanes,    normally    flat    but    flexi- 
ble,    upright    standards    connecting    the    mar- 
gins  of   said   aeroplanes,    said  standards   being 
connected     to     said     aeroplanes     by     universal 
joints,     diagonal     stay-wires     connecting     the 
opposite    ends    of    the    adjacent    standards,    a 
rope    extending    along    the    front    edge    of    the 
lower    aeroplane,    passing    through    guides    at 
the  front  corners  thereof,   and  having  its  ends 
secured  to  the  rear  corners  of  the  upper  aero 
plane,    and    a    rope    extending    along    the    rear 
edge   of  the  lower  aeroplane,   passing   through 


guides  at  the  rear  corners  thereof,  and  having 
its  ends  secured  to  the  front  corners  of  the 
upper  aeroplane,  substantially  as  described. 

18.  A  nying-machiue  comprising  two  su- 
perposed aeroplanes,  normally  flat  but  flexi- 
ble, upright  standards  connecting  the  mar- 
gins of  said  aeroplanes,  said  standards  being 
connected  to  said  aeroplanes  by  universal 
joints,  diagonal  stay-wires  connecting  the 
opposite  ends  of  the  adjacent  standards,  a 
rope  extending  along  the  front  edge  of  the 
lower  aeroplane,  passing  through  guides  at 
the  front  corners  thereof,  and  having  its  ends 
secured  to  the 'rear  corners  of  the  upper  aero- 
plane, and  a  rope  extending  along  the  rear 
edge  of  the  lower  aeroplane,  passing  through 
guides  at  the  rear  corners  thereof,  and  having 
its  ends  secured  to  the  front  corners  of  the 
upper  aeroplane,  in  combination  with  a  verti- 
cal rudder,  and  a  tiller-rope  connecting  said 
rudder  with  the  rope  extending  along  the 
rear  edge  of  the  lower  aeroplane,  substan- 
tially as  described. 

ORVILLE    WRIGHT 
WILBUR   WRIGHT. 
Witnesses : 

Chas.   E.  Taylor, 

E.  Earle  Forrer 


Specification  and  Claims  of  Montgomery  Patent. 


Issued  September  18,  1906. 

Expires  September  18,  1928. 

.  presently     describe.     These    rear    portions    a' 

Be  it   known   that   1,   John   J.    Montgomery,     and  b'   simply  rest  on  the  frame-bars  D,  and 

thereby    having    their    freedom    of    movement 
can  assume  various  positions,  like  the  arms  of 
balance,   thus  causing  a  change  in  the  form 


No.   831,173.  Filed  April  26,  19C6. 

To  all  whom  it  may  concern: 


a  citizen  of  the  United  States,  residing  at 
Santa  Clara,  county  of  Santa  Clara,  State  of 
California,  have  invented  certain  new  and 
useful  Improvements  in  Aeroplanes;  and  I  do 
hereby  declare  the  following  to  be  a  full, 
clear,  and  exact  description  of  the  same. 

My  invention  relates  to  the  class  of  aero- 
planes; and  it  consists  in  certain  surfaces 
with  means  for  adjusting  them,  as  I  shall 
hereinafter  fully  describe. 

The  object  of  my  invention  is  to  provide  a 
controllable  aeroplane  device. 

Referring  to  the  accompanying  drawings, 
Figure  1  is  a  side  elevation  of  my  aeroplane 
device.  Fig.  2  is  a  top  plan  of  the  same. 
Fig.  3  is  a  front  view  of  the  same.  Fig.  4  is  a 
plan,  enlarged,  of  one  side  of  one  wing-sur- 
face. Fig.  5  is  a  cross-section  on  the  line  x  x 
of  Fig.  4.  Fig.  6  is  a  detail  view  of  the  con- 
trolling wires  and  cords  which  change  the 
surface  of  the  aeroplane.  Fig.  7  is  a  detail 
view  of  the  same  adapted  for  the  rear  wing- 
Burface  of  the  aeroplane.  Fig.  7  is  a  detail 
view  of  the  same  adapted  for  the  rear  wing- 
surface  in  order  to  vary  its  inclination  to  the 
front  wing-surface. 

In  the  form  of  the  device  here  illustrated, 
there  is  a  front  wing-surface  A,  a  rear  wing- 
surface  B,  and  a  horizontal  tail-surface  C. 
The  wing-surfaces  A  and  B  in  fore-and-aft  or 
transverse  section  are  curved,  the  most  per- 
fect form  of  the  curve  being  that  of  a  parab- 
ola, whereby  the  curve  in  front  is  sharp  and 
that  in  the  back  is  relatively  more  gradual, 
as  seen  in  Fig.  5.  These  two  surfaces  A  and 
B  are  connected  by  the  bars  D  of  a  frame. 

The  front  portions  a  and  b,  respectively,  of 
the  wing-surfaces  are  best  curved  down  from 
center  to  ends,  as  seen  in  Fig.  3,  and  are 
firmly  attached  to  the  fore-and-aft  bars  D  at 
the  points  d.  They  are  also  strongly  braced 
in  all  directions  by  wires  d',  running  to  ver- 
tical frame-posts  d*  and  to  the  frame-bars  D. 
The  rear  portions  a'  and  b',  respectively,  of 
the  wing-surfaces  are  hinged  midway  of 
their  length,  where  their  stiffener-bars  are 
severed  and  hinged  together  at  a2  and  b2,  so 
that  said  rear  portions  are  free  to  droop,  but 
are  restrained  from  upward  movement  by  a 
series  of  wires  E,  attached  to  the  lower  beam 
F  of  the  frame  in  a  manner  which  I  shall 


a  balance,  thus  causing  a  change  n  the  form 
of  the  wing-surfaces  on  the  two  sides.  This 
change  of  surface  is  for  the  purpose  of  guid- 
ance and  partly  for  equilibrium  and  is  pro- 
duced by  the  following  means.  The  wires 
E,  which  are  attached  above  to  the  rear  por- 
tion a'  of  the  front  wing-surface  A,  pass 
downwardly  from  each  side  of  said  portion, 
the  group  of  wires  from  each  side  being 
united  below,  as  shown  in  Fig.  6,  to  opposite 
ends  of  an  equalizing-cable  e  through  the  in- 
tervention of  a  ring.  The  equalizing-cable  e 
plays  freely  through  a  pulley  e',  secured  on 
top  of  the  lower  beam  F  of  the  frame  of  the 
machine.  Secured  to  the  wing  terminals  of 
the  equalizer-cable  e  are  cords  e2,  which  pass 
therefrom  to  the  beam  and  cross  each  other 
through  a  guide  e4  on  said  beam,  and  thence 
said  cords  pass  downwardly  and  backwardly, 
as  seen  in  Fig.  1,  and  are  attached  to  the  ends 
of  a  cross-foot  or  stirrup-bar  G,  as  seen  in 
Figs.  2  and  3.  The  wires  E,  which  are  at- 
tached above  to  the  rear  portion  b'  of  the 
rear  wing-surface  B,  pass  downwardly  from 
each  side  of  said  portion,  the  groups  of  wires 
from  each  side  being  united  below,  as  shown 
in  Fig.  7,  to  opposite  ends  of  an  equalizing- 
cable  similar  to  the  cable  e  in  front  and  simi- 
larly lettered,  through  the  intervention  of  a 
ring.  This  rear  equalizing-cable  instead  of 
being  guided  by  a  pulley  firmly  attached  to 
the  beam  F  is  guided  and  plays  freely 
through  the  upper  pulley  of  a  triple  sheave, 
(lettered  e3),  which  sheave  is  connected  with 
and  held  by  a  cord  J,  attached  to  it.  This 
cord  J  passes  freely  through  a  hole  in  beam  F, 
as  seen  in  Fig.  7,  and  is  thence  guided  by  a 
pulley  j  under  the  beam  to  a  point  forward, 
as  shown  in  Fig.  1,  to  within  reach  of  the 
operator.  Cords  e2  are  secured  to  the  ter- 
minal rings  of  the  rear  equalizer-cable,  e,  as 
shown  in  Fig.  7,  and  thence  are  guided  by  the 
lateral  pulleys  of  the  triple  sheave  e3  down- 
wardly and  backwardly  to  the  foot  or  stirrup 
bar  G',  as  seen  in  Figs.  2  and  1.  By  pressing 
down  on  the  stirrup-bar  on  one  side  the  rear 
portions  of  the  wing-surfaces  on  one  side  are 
drawn  down,  while  those  on  the  opposite  side 
are  allowed  to  yield  to  the  air-pressure  be- 


458 


VEHICLES  OF  THE  AIR 


neath.  By  these  means  the  wing-surfaces 
change  their  form.  The  pressures  on  the 
two  sides  of  the  device  are  varied,  and  the 
device  may  keep  its  course  when  meeting  a 
gust,  which  would  tend  to  tilt  It  and  turn  it 
aside,  or  it  may  be  made  to  change  its  course. 

A  feature  of  the  arrangement  of  the  cords  e2 
(indicated  in  Fig.  6)  is  that  the  one  attached 
to  the  left  arms  passes  through  the  guide  E* 
to  the  right  end  of  the  stirrup-bar,  and  vice 
versa.  Thus  a  pressure  with  the  right  foot 
will  force  down  the  left  rear  surfaces,  making 
this  the  stronger  side  of  the  device,  while  the 
right  rear  surfaces  yielding  become  the 
weaker.  These  changes  cause  the  device  to 
swing  to  the  right. 

By  simultaneously  pressing  on  both  ends 
of  the  stirrup-bar  all  the  rear  portions  of  both 
wing-surfaces  are  depressed  for  the  purpose 
of  partly  meeting  the  requirements  of  the 
fore  and  aft  equilibrium;  but  this  is  mainly 
done  by  varying  the  relative  inclination  of 
one  of  the  wing-surfaces  to  that  of  the  other. 
This  last-named  variation  involves  both  fore 
and  aft  equilibrium  and  continuance  of  Sight, 
as  1  shall  presently  explain.  This  adjust- 
ment of  inclination  is  accomplished  by  al- 
lowing the  free  rear  portion  of  the  rear  wing- 
surface  B  to  rise  under  the  pressure  of  the 
air  and  by  pulling  it  down  again  as  required 
by  means  of  its  wires  E  and  cords  e2,  hereto- 
fore described,  which,  as  shown  in  Fig.  7,  are 
adapted  for  this  independent  use  as  the 
pulleys  e3  of  the  rear  control  are  not  secured 
to  the  beam  F,  but  are  held  by  a  separate 
cord  J,  which  passes  within  reach  of  the  op- 
erator, being  guided  by  a  pulley  j. 

In  the  rear  of  the  device  in  connection  with 
the  tail-surface  C  there  is  a  large  surface  H 

Perpendicular  to  the  tail-surface,  attached  to 
t  and  extending  both  above  and  below  it. 
The  tail-surface  is  adapted  to  swing  vertically 
by  being  hinged  at  c  to  the  rear  of  the  wing- 
surface  B  and  its  movement  is  effected  by 
means  of  a  cord  L,  secured  to  it  on  each  side, 
Fig.  1,  said  cord  being  suitably  guided  and  at- 
tached to  a  sliding  handhold  1  within  reach 
of  the  operator. 

The  surface  H  moves  vertically  with  the 
tail-surface;  but  it  has  no  side  movement,  be- 
cause its  function  is  that  of  a  keel  or  fin  and 
not  that  of  a  rudder.  It  serves  to  maintain 
the  side  equilibrium,  which  it  does  by  per- 
forming an  operation  different  from  that  of  a 
rudder.  The  essentials  of  this  fin-like  sur- 
face H  are,  first,  that  it  shall  be  relatively 
large;  second,  that  it  shall  be  proximately  to 
the  rear  surface,  and,  third,  that  it  shall  ex- 
tend above  and  below  the  tail-surface  C. 

Concerning  the  fore  and  aft  alined  wing- 
surfaces  A  and  B  there  are  two  essential  ad- 
justments, first,  that  of  the  rear  portions  of 
each  relatively  to  the  front  portions  and,  sec- 
ond, that  of  the  inclination  of  one  surface 
relatively  to  the  other.  By  the  first  adlust- 
ment  the  surfaces  undergo  changes  of  form 
and  the  effect  is  to  vary  the  air-pressures  on 
the  two  sides  of  the  machine,  whereby  the 
device  may  keep  its  course,  being  prevented 
from  tilting  or  turning  aside  and  may  change 
its  course.  These  results  are  based  upon  the 
essential  character  of  a  wing-surface.  In- 
vestigation has  shown  me  that  a  wing  Is  a 
specially-formed  surface  placed  in  such  a  po- 
sition as  to  develop  a  rotary  movement  in 
the  surrounding  air.  This  position  is  deter- 
mined by  mathematical  considerations.  The 
various  requirements  of  gliding  are  met  by 
changes  in  various  parts  of  the  wing.  The 
movements  in  the  air  are  of  such  a  nature  as 
to  make  it  possible  to  separate  the  wing-sur- 
face, as  I  have  done  in  my  device,  into  front 
and  rear  sections  and  maintain  the  special 
rotary  movement  of  the  air  which  lies  at  the 
basis  of  this  phenomenon.  The  sections 
though  separated  have  a  form  and  adjust- 
ment suitable  to  themselves,  based  upon  the 
fundamental  formula  of  formation  and  ad- 


justment, but  these  must  be  coordinate  to 
the  idea  of  one  larger  wing  of  which  they  are 
supposed  to  be  parts.  By  the  second  ad- 
justment— namely,  that  of  the  inclination  of 
one  wing-surface  relatively  to  the  other — the 
machine  maintains  equilibrium  and  flight. 
If  a  surface  moves  at  a  slight  angle  through 
the  air,  the  center  of  pressure  is  near  the 
front  edge,  and  the  weight  carried  must  be 
below  this  point.  To  meet  the  requirements 
of  varying  speeds  of  motion,  it  is  necessary  to 
either  change  the  position  of  the  weight  or 
the  angle  of  the  surface.  This  in  my  device  is 
done  by  changing  the  angle  between  the 
front  and  rear  wing  surfaces  A  and  B.  In 
the  process  of  gliding  there  must  be  a  con- 
tinual change  in  the  angle  of  these  surfaces 
to  maintain  the  proper  speed  and  equilibrium. 

Concerning  the  tail-surface  C  there  must 
be  an  up-and-down  or  vertical  adjustment. 
The  tail-surface  is  in  reality  but  an  extension 
of  the  rear  wing-surface  B.  By  the  varia- 
tion of  its  angle  the  pressures  in  the  rear  are 
varied.  The  same  variations  are,  indeed,  pro- 
duced if  the  tail  be  dispensed  with  and  the 
rear  wing-surface  is  changed  in  its  angle.  In 
other  words,  whether  the  tail  be  a  separate 
surface  or  only  an  extension  of  the  rear  wing- 
surface  it  Is  enough  to  say  that  the  rear  sur- 
face must  be  adapted  to  change  its  angle  in 
part  or  whole. 

The  effect  of  the  fin-like  surface  H  is  this: 
If  from  any  cause  the  machine  is  tilted  to  one 
side  and  it  commences  to  glide  sidewise, 
though  the  front  parts  have  an  unimpeded 
side  movement,  the  rear  part  having  the  large 
fin  H  meets  resistance  and  as  a  consequence 
the  machine  is  swung  around  and  continues 
to  travel  in  the  direction  it  started  to  fall. 
This  of  course  takes  the  machine  out  of  its 
course.  To  bring  it  back  again,  the  wings 
must  be  operated  as  before  described.  Thus 
it  will  be  seen  this  vertical  fin-like  surface 
has  a  distinctive  character,  due  to  its  size 
and  position,  and,  though  apparently  a  rud- 
der, is  the  reverse  and  not  designed  to  perform 
the  office  of  a  rudder. 

Heretofore  I  have  described  the  wing-sur- 
faces as  being  curved  in  cross-section,  the 
best  form  being  parabolic.  It  must  now  be 
noted  that  for  the  best  results  the  form  of 
each  side  of  each  wing-surface  is  specialized, 
as  follows:  All  the  fore-and-aft  or  cross  sec- 
tions are  parabolic  curves;  but  those  curves 
nearer  the  center  are  most  inclined  to  the 
path  of  movement  and  thence  toward  the 
ends  their  inclination  is  gradually  decreased, 
thereby  producing  a  sinuousity  of  the  wing, 
as  shown  in  Figs.  3  and  5,  which  is  the  nor 
mal  surface  from  which  the  various  changes 
are  made.  In  addition  to  this  adjustment 
or  arrangement  the  curved  cross-sections, 
beginning  about  two-thirds  from  the  center, 
are  less  sharply  curved  in  front,  and  so  con- 
tinue decreasing  in  sharp  curvature  to  the 
ends.  This  is  shown  in  Figs.  4  and  5,  where- 
in the  successive  sections  1,  2,  3,  and  4  show 
the  gradual  cutting  off  at  the  front  of  the 
sharp  beginning  of  the  several  parabolic 
curves.  The  first  of  these  arrangements— 
namely,  the  gradual  change  in  inclination  of 
the  cross-curves  to  the  path  of  movement- 
is  for  the  purpose  of  properly  meeting  and 
cutting  the  rising  current  of  air  immediately 
in  front  of  the  wing-surface,  analysis  and 
experiments  having  shown  that  the  action  of 
the  under  surface  of  a  wing  is  to  cause  an  as 
cending  current  of  air  immediately  in  front  of 
the  wing-surface,  this  ascending  tendency 
being  greatest  at  the  center  and  gradually 
diminishing  toward  the  tips.  The  second  ar- 
rangement—namely, the  diminishing  curva- 
ture near  the  ends  of  the  wing — of  the  for- 
ward end  of  the  curves  is  for  the  same  pur- 
pose, but  is  rendered  necessary  by  the  fact 
that  if  the  foregoing  adjustment  of  the  sur- 
faces were  continued  to  the  end  the  sharp 
curvature  of  the  front  edge  would  force  the 


FIGURE  260.— Montgomery  Patent  Drawings. 


460 


VEHICLES  OF  THE  AIR 


rear  portions  of  the  surface  into  a  too  abrupt 
position  relative  to  its  path,  thus  building  up 
a  large  unnecessary  resistance  to  the  forward 
movement. 

In  using  the  aeroplane  the  operator  sits 
astride  the  beam  F,  with  his  feet  on  the  stir- 
rup-bar O.  With  one  hand  he  holds  onto  the 
frame  and  with  the  other  he  holds  and  oper- 
ates the  cord  L  for  adusting  the  tail.  The 
machine,  with  the  operator  IB  place,  is  car- 
ried to  a  height  by  means  of  a  balloon  and  is 
launched  from  any  desired  elevation  by  trip- 
ping its  connections  with  the  balloon. 

Having  thus  described  the  invention,  what 
I  claim  as  Dew,  and  desire  to  protect  by  Let- 
ters Patent,  is — 

1.  In   an  aeroplane   device,   a   curved  wing, 
with  means  for  changing  its  curvature. 

2.  In  an  aeroplane  device,    a   curved   wing, 
with  means  for  adjusting  its  rear  portion  rela- 
tively to  its  front  portion,   to  change  its  cur- 
vature, 

3.  In  an  aeroplane  device,   a  curved  wing, 
with    means   for    adjusting    either    side    of    its 
rear   portion    either    similarly    to   or    diversely 
from    the   other,    relatively    to    the    front   por- 
tion,  to  change  its  curvature. 

4.  In  an   aeroplane  device,    a   curved  wing, 
having   a    rigid    front    portion    and    an    adjust- 
able   rear    portion    with    means    for    adjusting 
said  rear  portion  relatively   to  the   front  por- 
tion to  change  the  curvature  of  said  wing. 

5.  In    an   aeroplane   device,    a   curved    wing 
having  a  rigid  front  portion,  and  an  adustable 
rear  portion,   with  means  for  adjusting  either 
side  of  its  rear  portion  eithed  similarly  to  or 
diversely    from    the    other,    relatively    to    the 
front  portion,  to  change  its  curvature. 

6.  An   aeroplane   curved   parabolically  from 
front    to   rear,    with   means   for   changing   its 
surface. 

7.  An   aeroplane   curved    parabolically   from 
front    to    rear    with    means    for    adjusting    its 
rear  portion  relatively  to  its  front  portion,  to 
change  its  surface. 

8.  An   aeroplane   curved  parabolically   from 
front  to  rear  with  means  for  adjusting  either 
side  of  its  rear  portion  either  similarly  to  or 
diversely    from    the    other,    relatively    to    the 
front  portion,  to  change  its  curvature. 

9.  An    aeroplane   curved   parabolically   from 
front  to  rear,  its  front  portion  being  rigid,  and 
its    rear    portion    adjustable,    with    means    for 
adjusting    said  rear   portion   relatively    to    the 
front    portion,    to   change    the    surface    of    the 
aeroplane. 

10.  An      aeroplane      curved      parabolically 
from    front    to   rear,    its    front    portion    being 
rigid,    and    its    rear    portion    adustable,    with 
means  for  adjusting  either  side  of  its  rear  por- 
tion either  similarly  to  or  diversely  from   the 
other,     relatively     to    the    front     portion,     to 
change  its  curvature. 

11.  In   an   aeroplane    device,    plural   curved 
wings,  one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other and  changing  the  curvature  of  each. 

12.  In    an    aeroplace    device,    plural    aero- 
planes   curved     parabolically     from    front     to 
rear,   one   in  advance  of   another,    with   means 
for  varying  the  angle  of  one  relatively  to  an- 
other. 

13.  In    an    aeroplane    device    plural    aero- 
planes    curved     parabolically     from     front     to 
rear,    one  in  advance  of  another,   with   means 
for  varying  the  angle  of  one  relatively  to  an- 
other, and  changing  the  curvature  of  each. 

14.  In    an    aeroplane    device,     plural    aero- 
planes, one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other,  and  m«ans  for  adjusting  either  side  of 
the  rear  portion  of  each  aeroplane  either  simi- 
larly to  or  diversely  from  the  other  side,  rela- 
tively to  the  front  portion,  to  change  the  sur- 
face of  each  aeroplane. 

15.  In    an    aeroplane    device,    plural    aero- 
planes,    curved     parabolically     from    front    to 
rear,  one  in  advance  of  another,   with  means 


for  varying  the  angle  of  one  relatively  to  an- 
other, and  adjusting  the  rear  portion  of  each 
aeroplane  relatively  to  its  front  portion  to 
change  the  surface  of  each. 

16.  A    curved    aeroplane    with     means    for 
changing   its    curvature,    and   a   horizontal   tail 
behind,  with  means  for  swinging  it  vertically. 

17.  In    an   aeroplane    device,    plural    curved 
aeroplanes   one   in   advance  of   another,    and   a 
horizontal    tail-surface    behind    the    last    aero- 
plane  with    means   for   swinging   said   tail-sur- 
face vertically. 

18.  In    an    aeroplane    device,    plural    curved 
aeroplanes,    one    in    advance    of    another,    with 
means  for  varj-iug  the  angle  of  one  relatively 
to    another    and    a    horizontal    tail-surface    be- 
hind the  last  aeroplane  with  means  for  swing- 
Ing  said  tail-surface  vertically. 

19.  In    an    aeroplane    device,     plural    aero- 
planes, one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other and  changing  the  surface  of  each,   and  a 
horizontal    tail-surface    behind    the    last    aero- 
plane  with   means   for  swinging   said  tail-sur- 
face vertically. 

20.  In    an    aeroplane    device,     plural    aero- 
planes, one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other,  means  for   adjusting   either   side  of   the 
rear    portion    of    each    aeroplane    either    simi- 
larly to  or  diversely  from  the  other  side,  rela- 
tively to  the  front  portion,  to  change  the  sur- 
face of  each  aeroplane,   and  a  horizontal   tail- 
surface  behind  the  last  aeroplane   with  means 
for  swinging  said  tail-surface  vertically. 

21.  In    an    aeroplane    device,     plural    aero- 
planes,    curved     parabolically     from     front     to 
rear,    one  in   advance  of   another,    with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other, and  adjusting  the  rear  portions  of  each 
aeroplane   relatively    to   its   front    portions    to 
change  the  surface  of  each,   and  a   horizontal 
tail-surface    behind    the    last    aeroplane    with 
means    for    swinging    said    tail-surface    verti- 
cally. 

22.  An  aeroplane  having  at  its  rear  a  hori- 
zontal tail-surface  with  means  for  swinging  it 
vertically,    and    a    relatively    large    fin-surface 
fixed   to   the   tail-surface    perpendicularly. 

23.  A    curved    aeroplane    with    means    for 
changing   its   curvature   said   aeroplane   having 
at    its    rear    a    horizontal    tail-surface,     with 
means  for  swinging  it   vertically,   and  a  rela- 
tively   large    fin-surface  fixed   to    the    tail-sur- 
face perpendicularly. 

24.  An    aeroplane    device    comprising    plural 
aeroplanes  one  in  advance  of  another,   a  hori- 
zontal tail-surface  at  the  rear  of  the  last  aero- 
plane  with   means   for   swinging   it   vertically, 
and  a  relatively  large  fin-surface  fixed  to  the 
tail-surface  perpendicularly. 

25.  In    an    aeroplane    device,     plural    aero- 
planes one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other and  changing  the  surface  of  each,  and  a 
horizontal    tail-surface    behind    the    last    aero- 
plane,  with  means  for  swinging   said   tail-sur- 
face vertically,   and  a  fin-surface  fixed  to  the 
tail-surface   perpendicularly. 

26.  In    an    aeroplane    device,     plural    aero- 
planes, one  in  advance  of  another,  with  means 
for  varying  the  angle  of  one  relatively  to  an- 
other,  means  for  adjusting   either  side  of   the 
rear    portion    of    each    aeroplane    either    simi- 
larly to  or  diversely  from  the  other  side,  rela- 
tively to  the  front  portion,  to  change  the  sur- 
face of  each  aeroplane,   and  a  horizontal  tail- 
surface  behind  the  last  aeroplane  with  means 
for  swinging  said  tail-surface  vertically,  and  a 
fin-surface    fixed    to    the    tail-surface    perpen- 
dicularly. 

27.  In    an    aeroplane    device,    plural    aero- 
planes,    curved     parabolically     from    front    to 
rear,   one  in  advance  of  another,    with    means 
for  varying  the  angle  of  one  relatively  to  an- 
other,  and  adjusting  the  rear  portion  of  each 
aeroplane    relatively    to    its    front    portion    to 
change   the  surface  of  each   and  a  horizontal 


MISCELLANY 


461 


tall-surface  behind  the  last  aeroplane,  with 
means  for  swinging  said  tail-surface  vertically, 
and  a  fin-surface  fixed  to  the  tail-surface  per- 
pendicularly. 

28.  A    curved    aeroplane    with    means    for 
changing    its    curvature    and    provided   with,   a 
fin-surface  perpendicular  thereto. 

29.  A     curved    aeroplane    with    means    for 
changing    its    curvature    and    provided    with    a 
fin- surf  ace    perpendicular    thereto    and    extend- 
ing both  above  and  below  said  aeroplane. 

30.  An      aeroplane      curved      parabollcally 
from  front  to  rear. 

31.  An      aeroplane      curved      parabolically 
from   front  to  rear,    Its   curves,    In  successive 
sections  from  center  to  ends,  decreasing  in  in- 
clination to  the  path  of  travel. 

32.  An      aeroplane      curved      parabolically 
from  front  to  rear,   its  sections  near  the  ends 
being  less  sharply   curved   at  their  front  ends 
than  the  forward  ends  of  sections  nearer  the 
center. 

33.  An      aeroplane      curved      parabolically 
from    front   to   rear,    its    curves    in    successive 
sections  from  center  to  ends  decreasing  in  in- 
clination  to  the   path  of   travel,   and   its   sec- 
tions near  the  ends  being  less  sharply  curved 
at   their  forward  ends  than  the  forward  ends 
of  sections  nearer  the  center. 

34.  An      aeroplane      curved      parabolically 
from    front    to    rear,    its    curves    in   successive 
sections  from  center  to  ends  decreasing  in  in- 
clination   to   the    path   of    travel,    its    sections 
near    the    ends    being    less    sharply    curved    at 
their  forward  ends   than   the  forward  ends  of 
sections     near     the     center,     and     means     for 
changing  the  surface  of  said  aeroplane. 

35.  An       aeroplane       curved      parabolically 
from    front    to   rear,    its    curves    in    successive 
sections  from  center  to  ends  decreasing  in  in- 
clination  to   the   path   of   travel,    and   its   sec- 
tions near  the  ends  being  less  sharply  curved 
at  their  forward  ends  than  the  forward  ends 
of  sections  nearer   the   center,    and   means   for 
adjusting    the   rear    portion    of    said    aeroplane 
relatively  to  its  front  portion. 

36.,  An  aeroplane  curved  parabolically 
from  front  to  rear,  its  curves  in  successive 
sections  from  center  to  ends  decreasing  in  in- 
clination to  the  path  of  travel,  and  its  sec- 
tions near  the  ends  being  less  sharply  curved 
at  their  forward  ends  than  the  forward  ends 
of  sections  nearer  the  center,  the  front  por- 
tions of  said  aeroplane  being  rigid,  and  means 
for  adjusting  its  rear  portion  relatively  to  its 
front  portion,  to  change  its  surface. 

37.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to    rear,    its 
curves,    in   successive   sections   from    center   to 
ends,   decreasing  in  inclination  to  the  path  of 
travel,    and    a    horizontal    tail-surface    approxi- 
mate   to    the    rear    of    said    aeroplane,     with 
means    for    vertically    swinging    said    tail-sur- 
face. 

38.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to   rear,    its 
curves,    in   successive    sections   from   center  to 
ends,    decreasing  in  inclination   to  the   path   of 
travel,    a    horizontal    tail-surface    approximate 
to  the  rear  of  said  aeroplane,  with  means  for 
vertically    swinging    said    tail-surface,    and    a 
fin-surface     secured     perpendicularly     to     the 
tail-surface. 

39.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to    rear,    its 
curves,    in    successive    sections   from   center    to 
ends,    decreasing   in  inclination  to  the  path  of 
travel,    a    horizontal    tail-surface    approximate 
to  the  rear  of  said  aeroplane,  with  means  for 
vertically    swinging    said    tail-surface,     and    a 
fin-surface     secured     perpendicularly     to     the 
tail-surface     and     extending    both     above    and 
below  said  surface. 

40.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to    rear,    its 
curves    in    successive    sections    from    center    to 
ends  decreasing  in    inclination   to  the  path   of 
travel,    and   its   sections   near   the   ends   being 


less  sharply  curved  at  their  forward  ends 
than  the  forward  ends  of  sections  nearer  the 
center,  and  a  horizontal  tail-surface  approxi- 
mate to  the  rear  of  said  aeroplane,  with 
means  for  vertically  swinging  said  tail-sur- 
face. 

41.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to    rear,    its 
curves    in    successive    sections    from    center    to 
ends  decreasing  in   inclination   to  the  path  of 
travel,    and    its   sections   near   the    ends   being 
less    sharply    curved    at    their    forward    ends 
than  the  forward  ends  of   sections  nearer  the 
center,    a   horizontal    tail-surface    approximate 
to  the  rear  of  said  aeroplane,   with  means  for 
vertically    swinging    said    tail-surface,    and    a 
fin-surface     secured     perpendicularly     to     said 
tail-surface. 

42.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to   rear,    its 
curves.  In  successive  sections,   from  center   to 
ends,   decreasing  in  inclination  to  the  path  of 
travel,    with    means   for   changing    the   surface 
of  said  aeroplane,   and  a  tail-surface  approxi- 
mate   to    the    rear    of    said    aeroplane,     with 
means    for    vertically    swinging    said    tail-sur- 
face. 

43.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to    rear,    its 
curves   in   successive   sections   from    center    to 
ends   decreasing  in  inclination   to  the   path  of 
travel    and    its    sections    near    the    ends    being 
less    sharply    curved    at    their    forward    ends 
than   the  forward  ends  of   sections  nearer  the 
center,    with    means   for   changing   the  surface 
of  said  aeroplane,    and  a   tail-surface   approxi- 
mate to  the  rear  end  of  said  aeroplane,    with 
means    for   vertically    swinging    said    tail-sur- 
face. 

44.  In    an    aeroplane    device,    an    aeroplane 
curved    parabolically    from    front    to   rear,    its 
curves    in    successive    sections    from    center   to 
ends  decreasing  in   inclination  to  the   path   of 
travel,    and    its   sections   near    the    ends    being 
less    sharply    curved    at    their    forward    ends 
than   the  forward  ends   of  sections  nearer   the 
center,    with   means   for  changing   the   surface 
of    said    aeroplane,    a    tail-surface    approximate 
to  the  rear  end  of  said  aeroplane,  with  means 
for   vertically   swinging   said    tail-surface,    and 
a    fin-surface    secured    perpendicularly    to    the 
tail-surface. 

45.  An    aeroplane    device,    comprising    plu- 
ral   aeroplanes,    one    in    advance    of    another, 
with  means  for  changing  the  surface  of  each, 
and  means  for  varying  the  angle  of  one  rela- 
tively   to    another,     each    of    said    aeroplanes 
being  curved  parabolically  from  front  to  rear, 
its   curves   in   successive   sections   from   center 
to   ends   decreasing   in   inclination   to  the   path 
of  travel,  and  its  sections  near  the  ends  being 
less    sharply    curved    at    their    forward    ends 
than   the  forward   ends  of  sections  nearer  the 
center,    a    horizontal    tail-surface    approximate 
to  the  rear  portion  of  the  last  aeroplane,   and 
means  for  vertically  swinging  said  tail-surface. 

46.  An    areoplane    device,    comprising    plu- 
ral   aeroplanes,     one    in    advance    of    another, 
with   means  for   chaging   the   surface   of  each, 
and  means  for  varying  the  angle  of  one  rela- 
tively   to    another,     each    of    said    aeroplanes 
being  curved  parabolically  from  front  to  rear, 
its   curves    in    successive   sections    from    center 
to  ends  decreasing  in   inclination   to  the   path 
of  travel,  and  its  sections  near  the  ends  being 
less    sharply    curved    at    their    forward    ends 
than  the  forward  ends  of  sections  nearer   the 
center,    a    horizontal    tail-surface    approximate 
to    the    rear    portion    of    the    last    aeroplane, 
means    for    vertically    swinging    said    tail-sur- 
face,    and    a    fin-surface    secured    perpendicu- 
larly to  the  tail -surf  ace. 

In  witness  whereof  I  have  hereunto  set  my 
band. 

JOHN  J.  MONTGOMERY. 
In  presence  of — 
J.   Compton, 
D.    B.    Richards. 


462 


VEHICLES  OF  THE  AIR 


Claims  of  Chanute  Patent. 

No.  588,718.         Filed  December  7,  1895.     Issued  May  18,  1897.          Expires  May  18,  1914. 

1.     A  soaring-machine  having  a  rigid  frame 
comprising  a  hoop  A,  plates  K  pivoted  to  said 
hoop,  on  upright  pintles,  wings  L  attached  to 
*  plates,  and  contractile  members  N  lying 


SZT 


I,  the  wings  L  having  ribs  1  hinged  in  said 
plates,  and  the  elastic  cords  N  connecting  the 
front  ribs  with  the  hoop  A,  substantially  as 
described. 


FIQUBB  261. — Chanute  Patent  Drawing. 


in  the  plane  of  the  wings  and  attached  at  one 
end  to  the  hoop  and  at  the  other  end  to  the 
fronts  of  the  wings,  substantially  as  described. 
2.  In  a  soaring-machine,  the  combination 
with  the  framework  comprising  the  hoop  A, 
of  the  plates  K  pivoted  thereto  on  the  pintles 


In   testimony   whereof   I   affix   my   signature 
in  presence   of   two   witnesses. 

OCTAVE    CHANUTE. 


Charles  J.  Roney, 
Edw.  Barrington. 


Claims  of  Mouillard  Patent. 

»o.  582,757.          Filed  September  24,  1892.    Issued  May  18,  1897.       Expires  May  18,  1914. 


1.  A  soaring-machine  consisting  of  an  aero-  i 
plane    composed    of    two    wings,    each    hinged 
upon   a   vertical    axis   and  capable  of   forward 
and    backward    movement    only,    substantially 
as   described. 

2.  A     soaring-machine     consisting     of     two 
wings,     each     hinged     upon     a     vertical     axis, 
an     automatic     regulating     device     controlling 
the    angular    position   of    the    wings    with    the 
variation  in   speed,   substantially  as  described. 

3.  A     soaring-machine     consisting    of     two 
wings,   each  hinged  upon  a   vertical  axis,   and 
a    mechanical    device    attached    to   said   wings 
for  throwing   forward   the   tips  of   the   wings, 
substantially  as  described. 

4.  A     soaring-machine     consisting     of     two 
wings,   each  hinged  upon  a   vertical  axis,   and 
a  spring  attached  to  said  wings,  substantially 
as  described. 

5.  A     soaring-machine    consisting    of    two 
wings,   each  hinged  upon  a   vertical  axis,   and 
a    spring    normally    holding    the    tips    of    the 
wings  in    advance   of   said   axis,    substantially 
as  described. 

6.  A     soaring-machine     consisting     of     two 
wines,    each   hinged    upon    a   vertical   axis  but 
In   different   approximately   parallel   planes,   so 
that  one  can  close  partly  over  the  other,  sub- 
stantially AS  described. 

7.  A     soaring-machine     consisting     of     two 
wings,   each  hinged  upon  a  vertical  axis,   and 
each    having    a   tall    portion    adapted   to  close 
one  over  tfce  otter,  substantially  as  described. 


8.  A  soaring-machine  consisting  of  two 
wings,  each  hinged  upon  a  vertical  axis,  and 
adapted  to  close  one  over  the  other,  and  a 
mechanical  device  attached  to  said  wings  for 
positively  closing  them  at  will,  substantially 
as  described. 

0.  A  soaring-machine  consisting  of  two 
wings,  each  hinged  upon  a  vertical  axis,  and 
a  cord  attached  to  each  wing  and  running 
through  an  eye  in  the  other  wing,  for  clos- 
ing said  wings  together  substantially  as  de- 
scribed. 

10.  A     soaring- machine    consisting    of    two 
wings,   each  hinged  upon  a   vertical   axis,    and 
provided   with   stop-cords  to  limit   their   angu- 
lar movement,  substantially  as  described. 

11.  A    soaring-machine    consisting    of    two 
wings,    each  hinged  upon  a  vertical   axis,   and 
having  a  portion  movable  out  of  the  plane  of 
the  wing,   substantially   as   described. 

12.  A  soaring-machine  having  wings  adapt- 
ed to  move  in  horizontal  planes,   a  portion  of 
the  fabric  covering  each   wing  being  stiffened 
by  flexible  slats  and  having  its  rear  edge  free 
from    the    frame    of    the    wing,    and    cords    at- 
tached to  said  rear  edge  for  pulling  it  down- 
ward, substantially  as  described. 

13.  A    soaring-machine     consisting    of     two 
wings,   each   composed  of  a  framework,    a  net 

Sread    under   the   framework,    and   a   covering 
fabric    fastened    below    the    net,    substan- 
tially  as   described. 

14.  A  soaring-machine  consisting  of  an  ar 


MISCELLANY 


463 


talficial  sternum  adapted  to  be  fastened  to  the 
body  of  the  aviator  and  two  wings,  hinged  to 
said  sternum  on  an  upright  axis,  substantially 
as  described. 

15.  A  cuirass  or  corset  for  an  aviator  con- 
sisiting  of  a  rigid  breastplate  provided  with 
means  for  firmly  attaching  it  to  the  body,  and 
having  attachments  tor  receiving  and  sup- 


ed  to  hold  a  spring,  as  G,  substantially  as  de- 
scribed. 

18.  The  combination  with  the  rigid  breast- 
plate A  carrying  the  hooks  C,  D  of  the  wing, 
each  having  arms  F  provided  with  eyes  f  f 
to  fit  on  the  hooks,  substantially  as  described. 

10.  The  combination  with  the  rigid  breast- 
plate A  having  the  hooks  C,  D  and  the  clamp 


FIGURE  262. — Mouillard  Patent  Drawing. 


poiting    an    aeroplane,     substantially     as    de- 
scribed. 

16.  A  cuirass  or  corset  for  an  aviator,  con- 
sisting   of    a    rigid    breastplate    provided    with 
means  for  firmly  attaching  it  to  the  body,  and 
having  hooks  upon  which  a  pair  of  wings  may 
be  hinged  on  a  vertical  axis,  substantially  as 
described. 

17.  The  combination  with  the  cuirass  hav- 
ing a  rigid  breastplate  A,  of  the  hooks  C,   D, 
one  above  the  other,  and  a  clamp,  as  II,  adapt- 


H,  of  the  wings  each  having  arms  F  hinged 
upon  the  hooks,  and  the  flat  steel  spring  G 
held  at  its  middle  by  the  clamp,  and  having 
its  ends  attached  to  the  wings,  substantially 
as  described. 

In   testimony   whereof   I   affix   my  signature 
in  presence  of  two  witnesses. 

LOUIS    PIERRE    MOUILLARD. 
Witnesses: 

8.  Nuripoy, 
C.  P.  LugoW. 


Claims  of  Lilienthal  Patent. 


No.  544,816.      Filed  February  28,  1894.    Issued  August  20,  1895.    Expires  August  80,  1918. 


1.  In  a  flying  machine,   the  combination  of 
two  crossed  carrying  rods  a,  two  wings  vaulted 
upward,  and  strings  or  wires  i  extending  from  j 
the  ends  of  the  carrying  rods  toward  the  pe- 
ripheries of   the   wings,    substantially    as    set 
forth. 

2.  In  a  flying  machine,  the  combination  of 
two  crossed  carrying  rods  a,  two  wings  vaulted 
upward,  strings  or  wires  i  connecting  the  two 
carrying  rods   with   the  wings,   and  a  vertical 
fixed  rudder  substantially  as  set  forth. 

3.  In  a  flying  machine,   the  combination  of 
a   crossed  frame,   two  wings  connected   there- 
with, strings  or  wires  i,  a  vertical  fixed  rudder 
r  and  a  horizontal  tail  q,  adapted  to  turn  up- 
ward automatically,  substantially  as  set  forth. 

4.  In    a    flying    machine,    the    combination 
with  a  supporting  frame,  of  a  wing  adapted  to 
be  folded  together  and  having  its  ribs  diverg- 
ing   from    a    common    support,     and    suitably 
hinged   thereto  a   string  connecting   the  outer 
points  of   the  ribs,   and  continuous  fabric  at- 
tached to  a  series  of  ribs,  substantially  as  set 
Jorth. 

5.  In    a    flying    machine,    the    combination 
with   a   supporting   frame   comprising   a   hoop, 
of   a   wing   having  Its  ribs   diverging   from   a 
common  support,  a  string  connecting  the  outer 


points  of  the  ribs,  a  wire,  as  g,  fastened  to  the 
first  rib  of  the  wing  and  attached  to  the  hoop 
and  fabric  stretched  over  the  ribs  and  RUCO 
wire,  substantially  as  set  forth. 

6.  In    a    flying    machine,    the    combination 
with  a  supporting  frame,  of  a  wing  having  its 
ribs  diverging  from  a  common  support,   fabric 
stretched   over   the   ribs   and   wires,    as   i,   ex- 
tending  from   the  ribs   downward  to   the  sup- 
porting   frame    for    the    purpose    of    adjusting 
thereby  the  tension  of  the  ribs,   substantially 
as  set  forth. 

7.  In    a    flying    machine,    the    combination 
with  a   frame  comprising  a  hoop  and   crossed 
bars  connected  therewith,   of  wings  supported 
by  said  frame,  substantially  as  set  forth. 

8.  In  a  flying  machine,  a  supporting  frame 
for  the  wings  comprising  a   hoop  h,  rods  ex- 
tending   from    it   for   supporting    the   operator 
and  a  tail  and  a  rudder,  and  pockets  as  d  for 
receiving   the  ends  of  the  ribs  of  the  wings, 
substantially  as  set  forth. 

9.  In    a    flying    machine    the    combination 
with  a  supporting  frame,  of  wings  with  suit- 
able   ribs    connected    therewith,    front    tension 
wires  g,  and  pockets  d  for  receiving  the  inner 
ends  of  the  ribs,  the  ribs  being  made  capable 
of  turning  around  their  centers  in  such  pock- 


464 


VEHICLES  OF  THE  AIR 


ets  for  the  purpose  of  folding  up  such  wings, 
substantially  as  set  forth. 

10.  In  a  flying  machine,  the  combination 
with  a  supporting  frame,  of  wings,  a  fixed 
rudder  and  a  pivoted  tail  adjusted  to  come  to 
rest  upon  the  rudder  when  swinging  down- 
ward, substantially  as  set  forth. 


Signed  at  Berlin   this  1st  day  of  February, 

OTTO    LILIENTHAL. 
Witnesses: 

Herman  Muller, 
Reinhold    Weidner. 


FIGURE  263. — Lilienthal  Patent  Drawing. 

GLOSSARY  OF  AERONAUTICAL  TERMS 

The  rapid  and  extensive  recent  development 
in  aeronautics  has  given  rise  to  a  pressing  need 
for  proper  technical  terms  wherewith  to  charac- 
terize the  different  elements  of  the  new  mechan- 
isms without  ambiguity  or  awkward  circumlo- 
cution. In  the  English  language  this  need  has 
been  met  largely  by  borrowings  from  the  French, 
supplemented  by  a  number  of  new  significances 
given  to  common  woods.  Undoubtedly  it  is  the 
superior  richness  of  the  French  language  in  its 
technical  nomenclatures,  coupled  with  a  quite  char- 
acteristic fertility  in  the  invention  of  timely  words 
and  phrases,  that  has  enabled  France  thus  to  fasten 
so  much  of  its  aeronautical  terminology  upon  us. 

That  there  is  anything  objectionable  in  this 
situation,  or  in  the  often  railed-at  warping  of 
modern  meanings  away  from  archaic  significances, 


MISCELLANY  465 

is  likely  to  be  maintained  only  by  extreme  patriots 
or  purists.  The  generality  of  readers  and  writers, 
knowing  that  the  language  of  progressing  mankind 
must  itself  progress,  and  recognizing  that  usage 
is  here  the  court  of  last  resort,  will  welcome  the 
needed  additions  to  the  dictionary  with  as  little 
ado  as  may  be,  preferring  to  seek  definition  rather 
than  to  give  ear  to  denunciation. 

In  the  following  list  are  given  the  terms  from 
the  vocabulary  of  aeronautics  most  in  use  and  most 
in  need  of  definition.  No  pretension  to  complete- 
ness, finality,  or  authority  is  made  for  the  selection, 
which  is  offered  with  full  appreciation  that  it  will 
meet  both  criticism  and  amplification.  The  words 
here  given  are  from  a  variety  of  sources.  Some, 
as  has  been  suggested,  are  common  words  that  new 
needs  have  invested  with  new  meanings.  Others 
are  foreign  or  coined.  A  few  have  been  frankly 
originated  by  the  writer  in  the  hope  that  they  may 
meet  needs  not  otherwise  met.  And  many,  of 
differing  forms,  are  of  synonymous  meanings — 
included  with  the  idea  that  only  time  can  decide 
between  them. 


adjusting-  plane,    same  as  ADJUSTING  SURFACE. 

adjusting1  surface.  Commonly,  a  comparatively  small  surface,  usually  at 
the  end  of  a  wing  tip,  used  to  adjust  lateral  balance ;  preferably  restricted 
to  surfaces  capable  of  variable  adjustment  but  not  of  movement  by  con- 
trolling devices.  See  STABILIZER  and  WING  TIP,  and  compare  AILERON 

and   BALANCING    SURFACE. 

advancing  edge.    The   front   edge   of  a  sustaining  or   other  surface.     See 

FOLLOWING    EDGE. 

advancing-  surface.     A  surface  that  precedes  another  through  the  air,  as 

in  a  double  monoplane.    See  DOUBLE  MONOPLANE  and  FOLLOWING  SURFACE. 
aerocurve,   n.    A  proposed  substitute  for  AEROPLANE,  which  see. 
aerodrome,    n.    A  substitute  proposed  by  Langley  for  AEROPLANE,  which  see. 

Strictly  applicable  to  a  course  rather  than  to  a  vehicle, 
aerofoil,  n.     Another  proposed  substitute  for  AEROPLANE,  which  see. 
aeroplane,  n.      A   generic   term   applied   in    common   use   in    all    classes   of 

sustaining  surfaces ;  a  misnomer  to  the  extent  that  it  is  strictly  applicable 

only  to  flat  surfaces. 
aileron,   a'ler-dn,   n.      A   small   hinged   or   separated   wing   tip    or   surface, 

capable    of   independent   manipulation    for    the    purpose   of   maintaining 

lateral   balance.      See  BALANCING  PLANE   and  BALANCING   SURFACEJ   and. 

compare  ADJUSTING  SURFACE,  STABILIZER,  and  WING  TIP. 


466  VEHICLES  OF  THE  AIR 

air  speed,  n,      The    speed    of    an    aerial    vehicle    through    the    air,    as   dis- 

tinguished from  its  LAND  SPEED,  which  see. 
alighting  gear.     The  under  mechanism  of  an  aeroplane,  used  to  cushion  itc 

descent  and  to  bring  it  to  a  stop  as  it  reaches  the  ground.     See  RUNNER 

and  STARTING  DEVICE. 

angle  of  entry.  In  a  curved  aeroplane  surface,  the  angle  made  by  a  tangent 
to  the  advancing  edge  with  the  line  of  motion.  See  ANGLE  OF  INCIDENCE 

and   ANGLE    OF  TRAIL. 

angle  of  incidence.  In  a  curved  or  a  flat  aeroplane  surface,  the  angle  made 
by  the  chord  or  by  the  surface  with  its  line  of  travel.  See  ANGLE  OF 

ENTRY  and  ANGLE  OF  TRAIL. 

angle  of  trail.  In  a  curved  aeroplane  surface,  the  angle  of  a  tangent  to 
the  rear  edge  with  the  line  of  travel.  See  ANGLE  OF  ENTRY  and  ANGLE 

OF  INCIDENCE. 

apteroid,  ap'ter-oid,  a.  A  term  coined  by  Lanchester  to  designate  that  type 
of  wing  which  is  short  and  broad,  as  opposed  to  PTERYGOID,  which  see. 

arc.     Any  portion  of  a  circle  or  other  curve.     See  CHORD. 

arch.    A  down  curve  given  to  the  ends  of  a  wing  surface.    Compare  DIHEDRAL. 

aspect.    The  top  or  plan  view  of  an  aeroplane  surface.    See  ASPECT  RATIO. 

aspect  ratio.  The  proportion  of  the  length  to  the  width  of  a  wing  or 
aeroplane  surface.  See  ASPECT. 


aspiration,  n.  The  little-understood  phenomena  by  which  under  certain 
circumstances  an  air  current  flowing  against  the  edge  of  a  properly 
curved  wing  or  aeroplane  surface,  is  said  to  draw  such  surface  towards 


the  current.    See  TANGENTAL. 

attitude.  Same  as  ANGLE  OF  INCIDENCE,  which  see;  also  ace  FLYING  ATTITUDE 
and  GROUND  ATTITUDE. 

automatic  stability.  Applied  to  lateral  or  longitudinal  stability  maintained 
by  the  action  of  suitable  elements  on  mechanisms  independent  of  any 
control  exercised  by  the  operator  ;  there  is  a  tendency  to  restrict  the 
term  to  such  stability  secured  by  automatic  manipulation  of  controlling 
devices,  rather  than  to  systems  in  which  balance  is  maintained  by  the 
use  of  fins  or  dihedral  arrangements.  See  BALANCING  SURFACE  and 

STABILIZER. 

aviation,    a-vl-a'shun.    Dynamic  flight  by  means  of  HEAVIER-THAN-AIR  mechan- 

isms. 
aviator,  a'vl-a-ter.    The  operator  or  pilot  of  a  heavier-than-alr  flying  machine. 

B 

balance,  v.  To  maintain  equilibrium  by  hand  or  automatic  movement  of 
balancing  surfaces,  as  opposed  to  equilibrium  maintained  by  stabilizing. 
See  BALANCING  SURFACE,  and  compare  STABILIZE. 

balancing  plane.     Same  as  BALANCING  SURFACE. 

balancing  surface.  Any  surface  capable  of  automatic  or  other  manipula- 
tion lor  the  purpose  of  steering,  or  of  maintaining  lateral  or  longitudinal 
balance.  See  ADJUSTING  SURFACE,  AILERON,  ELEVATOR,  and  WING  WARPING, 
and  compare  STABILIZING  SURFACE  and  SUSTAINING  SURFACE. 

beat.  Occasionally  used  to  refer  to  the  periodicity  of  revolving-blade  or 
flapping-wing  movements. 

biplane,   bf'pZfln,  n.     an  aeroplane  with  two  superposed  main  surfaces.     See 

DOUBLE   MONOPLANE,  MONOPLANE,  TRIPLANE,  and   MULTIPLANE. 

body.  The  center  portion  of  an  aeroplane  or  other  aerial  vehicle,  in  which 
the  motor,  fuel  tanks,  passenger  accommodation,  etc.,  are  placed.  See 

FUSELAGE   and   NACELLE. 

brace,  n.  In  the  structure  of  an  aerial  vehicle,  a  frame  member  In  com- 
pression ;  preferably  restricted  to  diagonal  compression  members,  in 
contradistinction  to  STAY,  which  see,  and  therefore  not  the  same  thing 
as  a  STRUT,  which  see. 


camber,  n.  The  maximum  depth  of  curvature  given  to  a  surface  as  measured 
at  right  angles  from  the  chord  to  the  highest  point  of  the  surface. 

caster  wheel.  In  an  alighting  gear,  a  wheel  mounted  on  a  vertical  pivot 
forward  of  its  center  of  rotation,  so  that  it  automatically  turns  with 
changes  in  the  course  of  the  vehicle.  Compare  FIXED  WHEEL. 

cell.  A  boxlike  unit,  consisting  of  upper,  lower,  and  side  surfaces,  as  in  a 
box  kite;  used  to  afford  lateral  stability  by  the  action  of  its  vertical 
surfaces  and  longitudinal  stability  by  its  horizontal  surfaces. 


MISCELLANY  467 

center  of  effort.     The   point  or  axis  along  which  the  propulsive  effort  or 

thrust  of  one  or  more  propellers  is  balanced, 
center  of  gravity.     The  center  of  weight,  about  which  the  vehicle  balances 

in  all  directions. 
center  of  lift.     The  center  or  mean  of  one  or  more  centers  of  pressure.     See 

CENTER   OP   PBESSUEE. 

center  of  pressure.  Really  a  line  of  pressure,  along  the  under  side  of  a 
wing  or  aeroplane  surface,  on  either  side  of  which  the  pressures  are  equal. 

center  of  resistance.  The  point  or  axis  against  which  the  various  forward 
pressures  balance. 

center  of  thrust.     Same  as  CENTER  OF  EFFORT. 

chassis,  sha-se',  n.    The  under  structure  or  running  gear  of  a  vehicle. 

chord.  A  straight  line  drawn  between  the  ends  of  the  arc  of  a  circle  or 
other  curve.  See  ARC. 

compound  control.  A  system  of  control  in  which  two  separate  manipula- 
tions, as  of  a  vertical  or  horizontal  rudder,  are  effected  by  compound  or 
two-directional  movement  of  a  single  lever  or  steering  wheel. 

compression  side.  That  side  of  a  surface  or  propeller  blade  which  acts 
against  the  air ;  usually  the  lower  surface  in  the  case  of  wings  and  aero- 
planes. Compare  RAREFACTION  SURFACE. 

curtain,   n.     Same  as  PANEL. 


deck,  n.  A  main  aeroplane  surface,  used  particularly  with  reference  to  BI- 
PLANES and  MULTIPLANES,  which  see. 

demountable,  de-mount' able,  a.  Said  of  a  mechanism  designed  with  special 
provision  for  ready  taking  apart  and  reassembling. 

derrick,  n.  A  tower  in  which  a  falling  weight  is  dropped  to  start  an  aero- 
plane. 

diagonal.   A  diagonal  brace  or  stay  in  a  frame-work. 

dihedral,  dl-Jie'dral,  a.  Said  of  wing  pairs  inclined  at  an  upward  angle  to 
each  other.  Compare  ARCH. 

dirigible,  dlr-lg'ible,  a.    Steerable  or  navigable ;  applied  to  balloons. 

double  monoplane,  n.  A  monoplane  with  two  supporting  surfaces,  one  in 
advance  of  the  other.  Bee  ADVANCING  SURFACE,  FOLLOWING  SURFACE, 

•MONOPLANE,  and  MULTIPLANE. 

double  rudder,  n.  Any  rudder  in  which  there  are  two  surfaces,  usually  simi- 
lar in  size  and  outline. 

double-surfaced,  a.  Said  of  wings  or  aeroplanes  with  upper  and  lower  sur- 
faces, between  which  the  ribs,  wing  bars,  etc.,  are  concealed.  Compare 

SINGLE-SURFACED. 

down- wind,  adv.  Movement  in  the  direction  of  or  with  the  wind.  Compare 
UP-WIND. 

drift,  n.  The  aerodynamic  resistance  of  an  incorrect  wing  or  aeroplane  sur- 
face to  forward  movement,  as  distinguished  from  HEAD  RESISTANCE  and 
SKIN  FRICTION,  which  see.  Compare  LIFT. 

droop,  n.    Same  as  ARCH. 


elevator,  n.     A  term  that  has  come  into  general  use  to  describe  horizontally 

placed  rudders  for  steering  in  the  vertical  direction, 
ellipse.      One  of  the  conic  sections,  certain  portions  of  which  are  closely 

related   to   formation  and   development   of   correct   wing   sections.     See 

PARABOLA  and  HYPERBOLA. 

entry,  n.  A  term  that  refers  generally  to  the  whole  form,  angle  of  entry, 
angle  of  incidence,  etc.,  of  an  aeroplane  or  wing  surface  moving  through 
the  air.  See  ANGLE  OF  ENTRY,  ANGLE  or  INCIDENCE,  WING  SECTION. 

equivalent  head  area.  For  purposes  of  calculation,  an  area  of  unbroken  flat 
surface  having  a  head  resistance  equivalent  to  the  total  of  that  of  the 
various  struts,  bars,  braces,  stays,  etc.,  of  an  aerial  vehicle.  See  PRO- 
JECTED AREA. 


feathering,  a.  Said  of  surfaces  moved  in  such  manner  that  in  one  direction 
they  pass  edgewise  and  in  the  other  flatwise  through  the  air. 

fin,  n.  A  single  fixed  vertical  surface,  not  capable  of  movement  out  cf  its 
normal  plane.  See  STABILIZING  SURFACE. 


468  VEHICLES  OF  THE  AIR 

fish  section,  n.  A  term  applied  to  cross  sections  roughly  resembling  the 
body  of  a  fish,  blunt  in  front  and  more  finely  tapered  towards  the  rear  ; 
a  form  that  opposes  a  minimum  resistance  to  mevomcnt  through  the  air. 

fixed  wheel.  In  an  alighting  gear,  a  wheel  not  capable  of  being  turned  out 
of  its  normal  plane  of  rotation.  See  CASTER  WHEEL. 

flapping*  flight,  n.  Flight  by  means  of  more  or  less  rapidly  reciprocating  sur- 
face. See  HELICOPTEB,  ORNITHOPTER,  and  SOARING  FLIGHT. 

flexible  propeller,  n.  A  propeller  consisting  of  fabric  more  or  less  loosely 
mounted  on  a  framework,  so  that  it  can  adapt  its  form  to  the  air  pressures. 

flying*  attitude,  n.  The  angle  of  incidence  of  a  wing  or  aeroplane  surface  in 
flight,  as  opposed  to  its  angle  when  the  machine  is  resting  on  a  hori- 
zontal surface.  Compare  GROUND  ATTITUDE. 

flying-  angle.    Same  as  FLYING  ATTITUDE. 

following  edge.    The  rear  edge  of  a  wing  or  aeroplane  surface.     Compare 

ADVANCING  EDGE. 

following  surface.  A  sustaining  surface  that  is  preceded  by  another,  usu- 
ally similar.  Compare  ADVANCING  SURFACE. 

footpound,  ».  The  amount  of  energy  required  to  raise  one  pound  one  foot ; 
not  involving  the  element  of  time.  Set  HORSEPOWER. 

forced  pressure.  An  increase  in  the  pressure  of  air  adjacent  to  a  surface 
that  acts  upon  it.  Compare  FORCED  VACUUM. 

forced  vacuum.  A  lowering  in  the  pressure  of  air  adjacent  to  the  surface 
that  acts  upon  it.  Compare  FORCED  PRESSURE. 

fore-and-aft  stability.     Same  as  LONGITUDINAL  STABILITY. 

fuselage,  f&'sgl-Aj,  n.  The  framework  of  an  aerial  vehicle ;  preferably  re- 
stricted to  aeroplane  frameworks. 


gap,  n.  The  distance  between  two  adjacent  surfaces  in  a  biplane  or  multi- 
plane. 

gliding,  n.    Flying  down  a  slant  of  air  without  power. 

gliding  angle,  n.  The  angle  at  which  gliding  descent  is  made;  usually  the 
flattest  angle  at  which  a  machine  is  capable  of  descending.  Compare 

RISING  ANGLE. 

gliding  speed,  n.  The  speed  at  which  an  aerial  vehicle  glides  at  its  flattest 
angle  of  descent.  See  GLIDING  ANGLE. 

ground  attitude.  The  angle  of  incidence  of  an  aeroplane  surface  with  the 
machine  standing  on  the  ground,  as  opposed  to  its  angle  when  the  ma- 
chine is  in  flight.  Compare  FLYING  ATTITUDE. 

guy,  n.  A  wire  or  cord  connecting  with  a  more  or  less  remote  element  of  the 
mechanisms  of  a  flying  vehicle ;  preferably  restricted  to  such  wires  and 
cords  as  constitute  parts  of  the  controlling  system. 

gyroscope,  jl'rd-skdp,  n.     See  GYROSCOPIC  EFFECT. 

gyroscopic  effect.  The  property  of  any  rotating  mass  whereby  it  tends  to 
maintain  its  plane  of  rotation  against  disturbing  forces. 


hangar,  hang'&r,  n.     A  shed  for  housing  balloons  or  aeroplanes,  generally  the 

latter, 
head  resistance.      The   resistance   of  a  surface   to   movement   through   the 

air ;  closely  proportionate  to  its  projected  area.    See  DRIFT  and  PROJECTED 

AREA,  and  compare  SKIN  FRICTION. 
heavier-than-air,    a.     Applied    to    dynamic   flying   machines   weighing   more 

than  the  air  they  displace.    Compare  LIGHTER-THAN-AIR. 

height,  «.     Specifically,  the  maximum  vertical  dimension  of  an  aerial  vehicle. 
helicopter,   n.     A  dynamic  flying  machine,  of  the  heavier-than-air  type,  In 

which  sustension  is  provided  by  the  effect  of  screws  or  propellers  rotating 

on  vertical  axes, 
horizontal,  n.     A  term  suggested  for  a  level  plane  through  a  flying  machine 

when  it  is  in  flight,  as  opposed  to  a  similar  level  taken  when  the  machine 

is  standing  on  a  horizontal  surface, 
horizontal  rudder,   n.     A  horizontally  placed  rudder  for  steering  in  vertical 

directions.     Compare  VERTICAL  RUDDER. 
horsepower,  n.     A  rate  of  work  equivalent  to  the  lifting  of  33,000  footpounds 

a  minute.    See  FOOTPOUND. 


MISCELLANY  469 

hovejing-,  a.  Said  of  flying  in  which  practically  a  fixed  position  in  the  air 
is  maintained. 

hyperbola.  One  of  the  conic  sections,  believed  by  Lilienthal  to  be  the  cor- 
rect form  for  a  wing  section.  See  ELLIPSE  and  PARABOLA. 


keel.  A  longitudinally  placed  under-framing  for  stiffening  the  structure  of  & 
flying  machine ;  chiefly  employed  in  the  design  of  elongated  dirigible 
balloons. 


lattice  girder,  n.  A  stiff  and  light  structural  element  so  named  because  of 
the  resemblance  of  its  cris-crossed  members  to  lattice  work. 

lateral  stability,  n.  Stability  in  the  lateral  or  side-to-side  direction.  Com- 
pare LONGITUDINAL  STABILITY. 

laud  speed.     The  speed  of  an  aerial  vehicle  over  the  land  as  distinguished 

from  its  AIR  SPEED,  which  see. 
landing*  area.    A  special  surface  upon  which  flying  machines  can  alight  with 

minimum  risk  of  injury  from  obstructions.     See  STARTING  AREA. 
landing  skate.     Same  as  RUNNEB. 
leading  edge.     Same  as  ADVANCING  EDGE. 
leeway,  n.     Movement  at  right  angles  to  a  correct  or  desired  course  caused 

not  by  errors  in  steering,  but  by  lateral  drift  of  the  whole  body  of  the 

atmosphere. 
lift,  n.     The  sustaining  effect,  expressed  in  units  of  weight,  of  an  aeroplane 

or  wing  surface  ;  usually  compared  with  DRIFT,  which  see. 
lighter-than-air,  a.     Applied  to  an  airship  weighing  less  than  the  air  it  dis- 
places.   Compare  HEAVIER-THAN-AIR. 
longitudinal  stability.     Stability  in  the  longitudinal  or  fore-and-aft  direction. 

Compare  LATERAL  STABILITY. 

M 

main  deck.    Same  as  MAIN  PLANE,  which  see. 

main  plane.  Usually  the  largest  01  lowest  supporting  surface  of  a  multi- 
surfaced  aeroplane. 

main  landing  wheels.  In  an  alighting  gear,  the  wheels  that  take  the  chief 
shock  in  landing. 

mast,  n.  A  spar  or  strut  used  for  the  attachment  of  wire  or  other  stays  to 
stiffen  wings  or  other  parts  of  a  structure. 

monoplane,  n.  An  aeroplane  with  one  or  more  main  surfaces  in  the  same 
horizontal  plane.  See  DOUBLE  MONOPLANE,  and  compare  BIPLANE,  MULTI- 
PLANE, and  TRIPLANE. 

multiplane,  n.  An  aeroplane  with  two  or  more  superposed  or  otherwise 
arranged  main  surfaces  ;  often,  and  perhaps  preferably,  applied  to  aero- 
planes having  three  or  more  main  surfaces.  See  BIPLANE,  DOUBLE  MONO- 
PLANE, MONOPLANE,  and  TBIPLANE. 

N 

nacelle,  na-sel',  n.  The  framework  or  body  of  an  aerial  vehicle,  preferably 
restricted  to  dirigible  balloons.  See  FUSELAGE. 

negative  angle  of  incidence,  n.  An  angle  of  incidence  below  the  line  of 
travel ;  capable,  despite  a  common  impression  to  the  contrary,  of  affording 
considerable  sustension  with  correctly  curved  wing  surfaces. 


omithopter,  n.  A  dynamic  flying  machine,  of  the  heavier-than-alr  type,  in 
which  sustension  is  provided  by  the  effect  of  reciprocating  wing  surfaces. 

See  FLAPPING  FLIGHT,   ORTHOGONAL  FLIGHT,  and  AEROPLANE. 

orthogonal,  or-thog'o-nal,  a.  Flapping  flight  in  which  sustension  Is  pro- 
duced by  direct  reaction  of  the  air  in  a  certical  direction,  as  opposed 
to  sustension  secured  by  a  feathering  movement  of  the  wings.  See  FLAP- 
PING FLIGHT. 


470  VEHICLES  OF  THE  AIR 


panel,  n.     A  vertical  surface  in  a  box-kite-like  structure. 

parabola,  n.  One  of  the  conic  sections,  which  is,  with  certain  proper  modifi- 
cations, the  correct  curve  for  the  section  of  a  wing  surface ;  a  parabola 
is  practically  an  ellipse  with  its  other  focus  at  infinity.  See  ELLIPSE  and 

HYPERBOLA. 

partition,  n.    Same  as  PANEL. 

phugoid  theory,  fu'goid,  n.  A  theory  advanced  by  Lanchester  to  the  effect 
that  all  types  of  aeroplanes  naturally  fly  in  undulating  paths  with  the 
undulations  of  an  amplitude  and  a  period  determined  by  the  form  and 
size  of  the  structure. 

pilot,  n.    A  widely  preferred  term  for  the  operator  of  an  aerial  vehicle. 

pitch,  n.  The  amount  of  forward  movement  that  would  be  made  by  a  pro- 
peller in  the  course  of  one  rotation  were  it  to  progress  through  a  solid 
nut.  See  PROPELLER,  STRAIGHT  PITCH,  and  UNIFORM  PITCH. 

plane,  n.  Practically  a  flat  surface,  though  "aeroplane"  has  come  to  mean 
curved  surfaces  as  well.  See  AEROPLANE. 

polyplane,  n.    Same  as  MULTIPLANE. 

port,  n.    The  left  side  of  a  vehicle.    Compare  STARBOARD. 

projected  area,  n.  The  equivalent  flat  area  of  an  irregular  structure ;  the 
same  as  the  area  of  the  shadow  of  such  a  structure  cast  by  parallel  rays 
on  a  plain  surface.  See  EQUIVALENT  HEAD  AREA. 

propeller  reaction.  The  tendency  of  a  single  or  unneutralized  propeller  re- 
volving in  one  direction  to  revolve  the  vehicle  to  which  it  is  attached 
in  the  other  direction. 

pterygfoid,  a.  A  term  coined  by  Lanchester  to  designate  that  type  of  wing 
which  is  long  and  narrow,  as  opposed  to  APTEHOID,  which  see. 

pylon,  n.     Same  as  DERRICK. 

radial  spoke,  n.  In  a  wire  vehicle  wheel,  a  spoke  extending  radially  from 
the  nub  to  the  rim.  Compare  TANGENT  SPOKE. 


rarefaction  side,  n.  That  side  of  a  surface  or  propeller  blade,  opposite  that 
which  acts  against  the  air ;  usually  the  upper  surface  in  the  case  of 
wings  and  aeroplanes.  See  COMPRESSION  SIDE. 

reactive  stratum,  n.  The  compressed  stratum  of  air  flowing  beneath  an 
aeroplane  surface  or  behind  a  propeller  blade. 

rib,  n.  An  aeroplane  member  parallel  to  and  used  to  maintain  the  correct 
form  of  the  wing  sections.  Compare  STIFFENER  and  WING  BAB. 

rising-  angle,  n.  The  angle  at  which  an  aeroplane  ascends  in  the  air;  usu- 
ally the  steepest  angle  at  which  it  is  capable  of  ascending.  Compare 

GLIDING  ANGLE. 

rudder,  n.  A  vertical  or  horizontal  surface  for  steering  in  a  horizontal  or 
vertical  direction.  See  HORIZONTAL  RUDDER  and  VERTICAL  RUDDER. 

runner,  n.  Used  in  some  alighting  gears  in  preference  to  wheels  because  of 
the  better  action  upon  contact  with  the  ground. 


•crew,  n.    Same  as  PROPELLER. 

•emichord,  n.  The  part  of  a  chord  on  either  side  of  the  highest  point  of  the 
curve ;  not  necessarily  an  exact  half  of  the  chord.  See  CHORD. 

single-surfaced,  a.  Said  of  wings  or  aeroplanes  with  single  surfaces,  above 
or  below  which  the  ribs  and  wing  bars  are  placed.  Compare  DOUBLE- 
SURFACED. 

skid,  n.    Same  as  RUNNER. 

skin  friction,  n.  The  friction  of  the  air  against  the  surfaces  of  an  aerial 
vehicle. 

slip,  n.  The  amount  of  distance  lost  in  the  travel  of  a  propeller,  estimated 
by  comparison  of  the  distance  actually  travelled  in  a  given  number  of 
turns  with  the  distance  that  theoretically  should  be  travelled  as  figured 
from  the  PITCH.  See  PITCH. 

•oaring-  flight,  n.  The  flight  of  certain  large  birds  without  wing  flapping, 
differing  from  gliding  in  that  it  commonly  involves  upward  movement 
apparently  in  defiance  of  the  laws  of  force  and  motion,  though  some, 
without  well-established  reason,  suppose  it  to  be  accomplished  by  taking 


MISCELLANY  471 

advantage  of  rising  air  currents,  internal  air  movements,  etc.  Its  solu- 
tion and  imitation  constitute  one  of  the  problems  of  aerial  navigation. 

spar,  n.  A  term  in  more  or  less  common  use  to  describe  struts,  masts, 
braces,  etc. 

stabilize,  v.  To  maintain  equilibrium  by  the  action  of  surfaces  rather  than 
by  the  manipulation  of  devices. 

stabilizer,  n.  An  anglicised  form  of  the  French  "staWlisator."  Any  surface 
for  automatically  maintaining  lateral  or  longitudinal  balance.  See 

AUTOMATIC  STABILITY,  FIN,  LATERAL  BALANCE,  and  LONGITUDINAL  BAL- 
ANCE. 

stabilizing1  surface,  w.  Any  surface  placed  In  a  vertical  or  other  position, 
primarily  for  the  purpose  of  maintaining  equilibrium.  See  CELL,  DIHE- 
DRAL, FIN,  LATERAL  STABILITY,  and  PANEL,  and  Compare  BALANCING  SUR- 
FACE and  SUSTAINING  SURFACE. 

stable  equilibrium,  n.  said  of  machines  In  which  any  tendency  to  tip  over 
automatically  corrects  itself  without  the  use  of  automatic  balancing 
devices.  See  FIN. 

starboard,  n.    The  right  side  of  a  vehicle.    Compare  PORT. 

starting1  area.  A  special  surface  from  which  flying  machines  can  be 
launched  either  with  or  without  starting  devices.  See  LANDING  AREA  and 

STARTING   DEVICE. 

starting  device.     Any  device  for  launching  aerial  vehicles.     See  DERRICK, 

STARTING    IMPULSE,    STARTING   BAIL,   and   STARTING   TRUCK. 

starting-  impulse.  The  initial  thrust  required  for  starting  aeroplanes;  se- 
cured either  by  the  propeller  thrust  or  other  means  within  the  vehicle 
itself,  or  by  special  extraneous  appliances.  See  DERRICK,  STARTING  DE- 
VICE, STARTING  RAIL. 

starting-  rail,  n.     A   rail   on   which  an  aeroplane  Is  run   in  starting.     See 

STARTING  DEVICE,   STARTING  IMPULSE,  and  STARTING  TRUCK. 

starting1  truck,  n.  A  small  truck  upon  which  an  aeroplane  is  mounted 
while  there  is  imparted  to  it  the  initial  impulse.  See  STARTING  DEVICE, 

STARTING    IMPULSE,   and    STARTING  RAIL. 

stay,  n.  In  the  structure  of  an  aerial  vehicle,  a  frame  member  of  wire  or 
other  material.  See  BRACE. 

stiff ener,  n.  A  straight  bar  used  to  stiffen  a  flat  surface,  In  contradistinc- 
tion to  a  rib,  which  maintains  the  curvature  of  a  curved  surface.  Com- 
pare RIB. 

straight  pitch,  n.  In  an  aerial  propeller,  a  uniform  angle  of  blade  surface 
from  hub  to  tip,  so  that  the  different  portions  of  the  blade  do  not  ad- 
vance through  the  air  at  the  same  speeds.  Compare  UNIFORM  PITCH. 

strainer,  n.    Same  as  TURNBUCKLE. 

strut,  n.  A  compression  member  In  a  structure ;  particularly  applied  to 
vertical  members  separating  the  sustaining  surface  of  biplanes  and  multi- 
planes. See  BRACE  and  SPAR. 

strut  socket.  A  metal  or  other  socket  or  corner  piece  for  joining  struts  and 
other  frame  members. 

supplementary  surface,  n.  A  comparatively  small  surface  used  in  conjunc- 
tion with  larger  surfaces  for  some  special  purpose,  as  the  maintenance 
of  equilibrium,  for  steering,  etc.  See  AILERON,  FIN,  and  RUDDER. 

sustaining-  surface,  n.  Any  surface  placed  in  a  horizontal,  or  approximately 
horizontal  position,  primarily  for  the  purpose  of  affording  sustension. 
See  AEROPLANE  and  compare  BALANCING  SURFACE  and  STABILIZING  SUR- 
FACE. 


tail,  n.  A  rear  element  of  an  aeroplane  adapted  to  Improve  Its  stability  and 
often  affording  a  place  for  the  attachment  of  vertical  and  horizontal 
rudders,  stabilizing  devices,  etc.  See  CELL,  ELEVATOR,  and  RUDDER. 

tail  wheel,  n.  A  wheel  mounted  under  the  tail  of  an  aeroplane  to  support 
it  on  the  ground.  See  CASTER  WHEEL  and  RUNNING  GEAR. 

tangential,  a.  Applied  to  the  forward  inclination  of  the  sustaining  force 
with  certain  surfaces  at  certain  angles,  so  that  the  surface  tends  to 
move  into  the  wind.  See  ASPIRATION  and  DRIFT,  and  compare  LIFT. 

tangent  spoke.  In  a  wire  vehicle  wheel,  a  spoke  extending  on  a  tangent 
from  the  hub  circle  to  the  rim,  this  construction  affording  a  wheel 
adapted  to  transmission  of  power.  Compare  RADIAL  SPOKE. 

tie,  n.  A  wire  or  other  tension  member  connecting  two  points  in  a  struc- 
ture. See  STAY. 


472  VEHICLES  OF  THE  AIR 

tightener.  Any  device  for  tightening  a  stay  wire,  but  preferably  restricted 
to  tighteners  of  types  that  do  not  Involve  cutting  the  wire.  Compare 

TUBNBUCKLE. 

tractor  screw.     A  propeller  placed  In  front  of  a  vehicle,  so  that  it  pulls  In. 

stead  of  pushes  it  through  the  air. 
traveling1  speed,  n.     Same  as  GLIDING  SPEED,  which  see;  also  used  to  refer 

to  the  maximum  speed  of  an  aeroplane, 
triplane,   n.     An   aeroplane   with   three   main   surfaces.     Compare  BIPLANE, 

DOUBLE  MONOPLANE,  and   MONOPLANE. 

trochoidal,  tro'koyd-Hl,  a.  A  term  coined  by  Hargrave,  a  trochoidal  plane 
being  denned  by  him  as  "a  flat  surface,  the  center  of  which  moves  at  a 
uniform  speed  in  a  circle,  the  plane  being  kept  normal  to  the  surface 
of  a  trochoidal  wave,  having  a  period  equal  to  the  time  occupied  by  the 
center  of  the  plane  in  completing  one  revolution." 

turnbuckle.  A  device  with  a  right  and  left-hand  screw  for  tightening  wire 
ties  and  stays.  Compare  TIGHTENER. 


uniform  pitch.  In  an  aerial  propeller  a  varying  angle  of  blade  surface  from 
hub  to  tip,  so  that  all  portions  of  the  blade  tend  to  advance  through 
the  air  at  the  same  rate  of  speed.  See  PITCH  and  STRAIGHT  PITCH. 

up-wind,  adv.  Movement  In  a  direction  directly  against  the  wind.  Compare 
DOWN-WIND. 


vertical  rudder.  A  vertically-placed  rudder  for  steering  in  horizontal  direc- 
tions. Compare  HORIZONTAL  RUDDER. 

W 

wake,  n.  The  trail  of  disturbed  air  left  by  a  moving  aerial  vehicle,  invis- 
ible, but  in  a  way  resembling  the  wake  of  a  ship  in  its  effect  upon  other 
vehicles  that  pass  into  it.  See  WASH. 

wash,  n.  Lateral  oscillations  of  air  sent  out  from  the  sides  of  an  aerial 
vehicle ;  invisible  as  in  the  case  of  the  foregoing  except  by  their  effect 
upon  adjacent  vehicles.  See  WAKE. 

wing"  arc,  n.      The   arc    of   movement   of  a   flapping   wing.      See   FLAPPING 

FLIGHT    and   ORNITHOPTER. 

wing  bar.  A  longitudinal  strengthening  member  in  a  wing  or  aeroplane, 
running  from  tip  to  tip  and  crossed  at  right  angles  by  the  ribs.  See 

RIBS. 

win?  girder,   n.     Same   as   wing  bar,   excepting   that  it  usually   implies  a 

more  elaborately  built-up  construction. 
wing  plan,    n.     The  outline  of  a  wing  or  aeroplane   surface  viewed  from 

directly  above  or  below. 
wing  section.     The  fore-and-aft  curvature,  to  the  path  of  movement,  in  the 

sections  of  a  wing  or  aeroplane.     See  AEROPLANE,  ELLIPSE,  HYPERBOLA, 

and  PARABOLA. 
wing  skid.     A   small   runner   under   the  tip   of   a    wing  to   protect  it  from 

damage  by  coming  in  contact  with  the  ground.     Compare  WING  WHEEL. 
wing  tip.   The  extreme  outer  end  of  a  wing,  often  made  movable  or  capable 

of  warping,  to  control  lateral  balance.     See  AILERON  and  WING  WARPING. 
wing  warping.     A    system   of    maintaining    lateral    balance   by    differential 

twisting  of  wing  tips,  in  such  manner  as  to  increase  the  sustension  on 

one  side  and  decrease  it  on  the  other. 
wing  wheel.    A   small    wheel   under   the  tip   of  a   wing  to   protect   it   from 

damage  by  coming  in  contact  with  the  ground. 


CHAPTER  FIFTEEN 

FLIGHT  EECORDS 

Much  interest  naturally  attaches  to  the  various 
records  that  have  been  made  with  flying  machines, 
for  which  reason  there  is  herein  presented  in  tabu- 


FIOURE  264. — Diagrammatic  Comparisons  of  Modern  Aeroplanes.  A,  Santos- 
Dumont  Monoplane ;  B,  Bleriot  Mono  plane ;  C,  Curtiss  Biplane ;  D,  Volsiu 
Biplane  ;  E,  R.  E.  P.  Monoplane  ;  F,  Antoinette  Monoplane  ;  G,  Wright  Biplane : 
H,  Cody  Biplane. 

473 


474 


VEHICLES  OF  THE  AIR 


lar  form  the  most  complete  record  yet  published 
of  such  flights,  together  with  maps  of  the  more  im- 


FIGURE  266.  —  Farman 
Flights,  Chalons  to  Rheims, 
and  Chalons  to  Suippes. 


FIGURE  265. — Flights  over  -English 
Channel.  The  Boulogne-Folkstone 
flight  has  not  been  accomplished,  but 
a  prize  is  offered  for  It. 


portant  cross-country  trips. 

Of  the  latter,  the  greatest 

interest    perhaps    attaches 

to  Bleriot's  crossing  of  the 

English  Channel  with  his  re- 
markable little  monoplane  (see 
Figure  265),  Henry  Farman 's  first 
trip  from  Chalons  to  Rheims  and 
then,  at  a  later  date,  from  Chalons 
to  Suippes  (see  Figure  266)  ;  Count 
de  Lambert's  flight  with  a  Wright 
biplane  from  Juvisy  to  Paris  (see 
Figure  267),  Paulhan's  flight  from 
London  to  Manchester,  Curtiss' 
flight  from  Albany  to  New  York, 
and  Captain  Roll's  round-trip  flight 

across  the  English  Channel  and  Hamilton's  flight 

from  New  York  to  Philadelphia  and  return. 


FIGURE  267. 


FLIGHT  RECORDS 


475 


In  the  tabular  history  that  follows  are  given 
the  full  particulars  of  every  flight  of  special  impor- 
tance or  interest  from  the  earliest  times  to  the  end 
of  1909.  Subsequent  to  this  date  there  are  ap- 
pended the  particulars  of  only  those  flights  that 
constitute  new  records,  those  that  have  occupied 
an  hour  or  more,  those  that  have  involved  a  speed 
and  distance  substantially  equivalent  to  this  time, 
and  those  which  have  resulted  in  fatality. 


.1503 

APRIL  i. 


z  , 


JiALTLHSURG- 


.. 

O 


FIGURE    268. — Map    Showing    Principal  Zeppelin   Plights. 


476 


VEHICLES  OF  THE  AIR 


AlftKCHWTIR 


LONDON 


FIGURE  269. 


It  was  originally  the 
author's  intention  to  con- 
tinue to  chronicle  every 
flight,  however  brief  in 
duration,  but  at  this  writ- 
ing it  is  the  fact  that  aero- 
nautical development  has 
progressed  too  fast  and 
far  for  detailed  track  to  be 
kept  of  every  minor  flight 
— the  attempt  to  record 
which,  now,  might  be 

fairly  likened  to  an  attempt  to  tabulate  every  run 
of  all  automobiles  in  the  world  when  this  allied 
industry  had  reached  something  less  than  its  pres- 
ent great  development. 

As  nearly  as  can  be  ascer- 
tained with  reasonably  thor- 
ough investigation,  the  pres- 
ent total  distance  flown  is 
mounting  up  at  the  rate  of 
at  least  4,000  miles  a  week 
(chiefly  in  France)  and  the 
aggregate  is  well  past  the 
200,000  mile  mark. 

In  all  this  flying  there 
have  befallen  only  eight  fa- 
tal accidents,  and  in  each  of 
these  cases  it  is  more  or  less 
clearly  evident  that  the  un- 
fortunate result  was  due  to 
some  preventable  careless- 
ness or  recklessness  rather 
FIGURE  270.  than  to  any  inherent  danger 


FLIGHT  RECORDS  477 

inseparable  from  the  reasonably  judicious  use  of 
the  new  vehicles  of  the  air. 

For  example — as  is  mentioned  in  the  remarks 
in  the  table — the  first  accident,  in  which  Lieutenant 
Selfridge  of  the  United  States  Army  was  killed, 
occurred  during  the  first  flight  of  a  Wright  ma- 
chine after  the  propellers  had  been  lengthened  from 
8*/2  feet  to  9  feet,  in  an  effort  to  increase  the  pre- 
vious speed  of  38  miles  an  hour  to  40  miles,  for  the 
purpose  of  making  good  the  demands  of  a  govern- 
ment test.  Unfortunately,  the  lengthening  of  the 
propellers  was  done  without  providing  the  proper 
clearance  between  their  tips  and  the  wire  guys  to 
the  vertical-rudder  struts,  with  the  result  that  one 
of  these  was  chopped,  a  propeller  blade  broken,  and 
the  machine  careened  to  the  ground  by  the  now 
unbalanced  drive  of  the  other  propeller  and  the 
effect  of  the  loosened  vertical  rudder. 

The  next  accident,  in  which  Eugene  Lefebvre 
lost  his  life,  was  also  due  to  a  Wright  machine, 
which  was  making  its  first  trial.  The  machine  was 
flying  very  close  to  the  ground  and  the  smash  was 
not  so  violent  but  what  the  operator  might  have 
escaped  serious  injury  had  not  the  motor  happened 
to  break  loose  and  fall  upon  him.  Eye  witnesses 
of  the  affair  assert  that  the  forward  elevator 
seemed  to  come  loose,  apparently  because  of  hur- 
ried or  careless  assembling. 

The  third  fatal  accident  in  the  history  of  power- 
driven  heavier-than-air  machines  was  even  more 
than  the  foregoing  due  to  an  unfortunate  combina- 
tion of  circumstances  rather  than  to  a  necessarily 
dangerous  situation.  In  this  case,  Captain  Ferdi- 
nand Ferber,  of  the  French  Army,  had  brought  his 


478  VEHICLES  OF  THE  AIR 

Voisin  biplane  safely  to  the  ground  and  was  run- 
ning on  the  wheels  of  the  alighting  gear,  when  one 
of  the  wings  tipped  down  and  upset  the  machine 
in  such  a  manner  that  its  operator  was  struck  by 
the  motor.  Ferber  walked  about  for  a  short  time, 
and  was  not  thought  to  be  badly  hurt,  but  soon 
died  from  internal  injuries. 

The  fourth  fatality,  in  which  Fernandez  was 
the  victim,  was  clearly  due  to  carelessness,  the  un- 
fortunate aviator  ignoring  the  protests  of  his 
mechanician  and  going  aloft  in  a  biplane  of  his 
own  make  (somewhat  resembling  the  Curtiss) 
with  a  control  wire  tied  up  with  a  bit  of  string. 
The  string  broke,  and  the  fall  was  inevitable. 

Leon  Delagrange,  who  was  the  first  to  meet 
death  in  a  monoplane,  likewise  paid  with  his  life 
for  an  avoidable  disregard  of  most  elementary  me- 
chanical principles.  His  last  machine  was  a  Bleriot, 
designed  for  a  speed  of  about  30  miles  an  hour  with 
a  light,  22-horsepower  Anzani  motor.  But  Dela- 
grange, against  Bleriot 's  advice,  substituted  a  heav- 
ier, 50-horsepower,  Gnome  motor,  and  produced  a 
speed  of  45  miles  an  hour.  On  top  of  this  he  re- 
moved from  the  frame  some  struts  he  thought  un- 
necessary, and  the  pressure  of  the  wings,  which 
sagged  the  frame  bars  apart  with  the  machine  on 
the  ground,  crushed  them  together  in  the  air.  In 
the  resulting  fall  of  60  or  70  feet,  Delagrange  had 
his  skull  fractured  by  the  motor. 

The  sixth  martyr  to  the  science  of  aviation  was 
Hubert  Le  Blon,  who  in  using  a  Bleriot  machine, 
modified  in  almost  the  identical  fashion  of  the  one 
that  killed  Delagrange,  proved  that  his  established 
reputation  for  recklessness,  both  as  a  motorist  and 


FLIGHT  RECORDS  479 

aviator,  was  not  unfounded.  Though  the  struts  in 
the  frame  were  not  removed,  Le  Blon's  last  flight 
was  in  a  dangerously  high  wind,  at  San  Sebastian, 
Spain,  and  there  is  much  probability  that  the  gyro- 
scopic action  of  the  heavy  revolving  motor  tore  it 
loose  from  its  light  attachments  in  executing  a  short 
turn.  Le  Blon  fell  with  the  machine  into  shallow 
water,  and,  apparently  stunned  by  the  fall,  was 
held  three  feet  beneath  the  surface  for  about  eight 
minutes  before  he  could  be  reached.  Drowning  was 
the  direct  cause  of  death. 

The  exact  cause  of  the  seventh  fatal  accident,  to 
young  Michelin,  of  France,  was  careless  flying  in  a 
wind,  near  obstacles. 

Considering  the  present  total  mileage  of  flight 
accomplished,  the  infancy  of  the  science,  and  the 
dangerous  unnecessary  risks  that  have  been  fool- 
ishly taken,  it  is  fairly  to  be  held  that  the  showing 
of  safety  for  the  aerial  vehicle  compares  favorably 
with  the  earlier,  and  even  with  the  later,  periods 
of  much  longer  established  developments  in  various 
fields  of  practical  and  commercial  transportation. 

In  the  matter  of  the  hour  flights  that  are  here 
recorded,  it  is  perhaps  interesting  to  note  that  there 
are  today  no  less  than  forty-five  or  fifty  men  who 
have  piloted  some  eight  different  aeroplanes  in 
flights  of  this  duration. 


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III 


491 


INDEX 


Desforges 120 

Accessories 410 

Acetylene    410,  413 

Acetylene  and  Oxygen 416 

Acetylene  Burners 415 

Acetylene  Generators  414 

Action  and  Reaction 194 

Action,  Radii  of 436 

Adams-Parwell  Revolving  Motor 129 

Ader,  Clement    120,  134,  140,  229,  392 

Ader's  Steam  Aeroplane 134 

Ader's  Avion 151 

Adjustable  Ball  Bearings 328 

Aerial  Experiment  Association   154,  229,  360,  438 

Aerial  Metal 384 

Aerial  Navigation 446 

Aerial  Travel,  Influence  of  Wind  on 437 

Aerial  Travel  Over  Water , 38 

Aerial  Vehicles,  Design  of 443 

Aerial  Vehicles,  Applications  of 428 

Aerodynamics,  Laws  of 170 

Aeronautic  Society 450 

Aeronautical  Congress  of  1893,  Montgomery  Paper  Presented  to 174 

Aeronautical  Development    23 

Aeronautical  Society  of  Great  Britain 233 

Aeronautical  Terminology    464 

Aeronautical  Terms    464 

Aeroplane  Analogies    26 

Aeroplane  Details    158 

Aeroplane,  Fighting  (Utility  of  in  War 37 

Aeroplane,  Framing   230 

Aeroplane  History 13J 

Aeroplane  Most  Promising   26 

Aeroplane  a  Misnomer   26 

Aeroplanes,  Analogies  in  Nature 159 

Aeroplanes,  Balancing   215 

Aeroplanes,  Building  and  Testing 395 

Aeroplanes,  Efficient  Modern   434 

Aeroplanes,  Typical    394 

Air  an  Elastic  Fluid 52 

Air,  Compressed 309 

Air  Cooling    290 

493 


494  INDEX— Continued 

Air  in  Advance  of  Surface,  Effect  of  Surface  Upon 172,  174 

Air  in  Motion  50 

Air,  Liquid   50,  309 

Air,  Mobility  of 63 

Air,  Properties  of 49 

Airships  Versus  Battleships 36 

Alexander 120 

Alighting  and  Starting 35tf 

Alighting  Gears  369 

Allard    120 

Alloy  Steel   383 

Alloys,  Aluminum  384 

Aluman    384,  393 

Aluminum    393 

Aluminum  Alloys     384 

Aluminum  Bronze .386,  393 

Aluminum  Paint    388 

Ammonia  Gas  102 

Anemometers    420 

Aneroid  Barometers   424 

Angle  of  Incidence    204 

Angle  of  Incidence,  Effect  of  Excessive 204 

Angle  of  Incidence,  Proper  Determination  of 186 

Animals  and  Aeroplanes,  Flying 162 

Animal  Flight,  Deductions  from 159 

Animal  Oils   354 

Annular  Ball   Bearings 33 

Antoinette    Monoplanes 31,  142,  155,  168,  208,  218,  312,  358,  396,  440 

Antoinette    Motors 85,  280,  289 

Anzani  Engines   280,  281,  398 

Applewood 292,  375 

Applications  of  Aerial  Vehicles 428 

Archdeacon    140,  153 

Arc  Lamps   411 

Arcs  of  Circles 172 

Archyta* 118,  119 

Argentallum    385 

Arlandes,  Marquis  d' 70 

Artingttall    120 

Ash 375 

Assembling    392 

Atmosphere,  Composition  of 45,  46 

Atmosphere,  Extent  of 43 

Atmosphere,  Height  of   43,  44 

Atmosphere,  "Permanent  Inversion  Layer"  in 55 

Atmosphere,  The    "Homogeneous" 43 

Atmosphere,  Tidal  Currents  in 58 

Atmosphere,  Weight    of 43,  45 

Atmospheric  Electricity 64 

Atmospheric  Properties  and  Phenomena 43 

Autogenous  Welding  391 

Automatic  Equilibrium 221 

Auxiliary  Exhausts   297 

Avcrv,  William 136 


INDEX— Continued  495 

B 

Babbitt    • 343 

"Baby,"  English  Dirigible 83 

Bacqueville,  Marquis  de 120 

Balance,  Lateral   215 

Balancing  Aeroplanes    215 

Balancing  by  Dihedral  Angle 216 

Balancing  by  Vertical   Surfaces    216 

Balancing  by  Wing  Warping    216 

Baldwin    85,  120 

Bail-Bearing  Sizes,  Capacities,  and  Weights 336 

Ball  Bearings 328 

Ball  Thrust  Bearings , 333 

Ballast,  First  Use  of 71 

Ballast,  Sand    109 

Ballast,  Water    109 

Balloon  An  Evasion  Rather  Than  Solution 24 

Balloon  Baskets    380 

Balloon  Duration  Record 74 

Balloon  Envelope   Materials    91 

Balloon  Envelopes,  Sheet  Metal 92 

Balloon  Fabrics,    Cotton 93 

Balloon  Fabrics,  Gas-proofing    95 

Balloon  Fabrics,  Linen     94 

Balloon  Fabrics,  Paper    94 

Balloon  Fabrics,  Silk 93 

Balloon,  First  Captive   70 

Balloon,  First   Hydrogen 71 

Balloon-height  Control    106 

Balloon  Housings    115 

Balloon  Inflation 96 

Balloon  Landing  Pits 116 

Balloon  Nettings    103 

Balloon  Valves    107 

Balloons,  Dirigible    76 

Balloons,  Early  Chinese  Ascensions  with 66 

Balloons,  Heated-air     49 

Balloons    in  Siege  of  Paris 74 

Balloons,  Internal   Ill 

Balloons    in  War 73 

Balloons,  Limitations  of    78 

Balloons,  Non-dirigible    66 

Balloons,  Non-lifting     107 

Balloons,  Soap  Bubble    67 

Balloons,  Spherical 75 

Balloons,  Sounding 44 

Balloons,  Vacuum     67 

Bamboo 375,  392 

Bamboo,    Split    375 

Barometers    424 

Barometers,  Aneroid 424 

Barometers,   Mercurial    424 

Barton,  Dr . 83 

Baskets,  Balloon    380 


496  INDEX— Continued 


Bats   165 

Bats,  Soaring , 165 

Bearings    327 

Bearings,  Adjustable  Ball    328 

Bearings,  Annular  Bali 330 

Bearings,  Ball    328 

Bearings,  Ball   Thrust    333 

Bearings,  Cone    346 

Bearings,  Cylindrical  Roller    340 

Bearings,  Flexible   Roller    340 

Bearings,  Plain    342 

Bearings,  Roller     339 

Bearings,  Scraping  Plain 345 

Bearings,  Tapered  Roller 341 

Beech     392 

Beedle    83 

Bell,  Alexander  Graham 137,  139,  153,  263 

Belt,  Link   317 

Belts  and  Pulleys 324 

Berliner,  Emil   125 

Berliner  Helicopter   129 

Berliner  Helicopter,  Data  Concerning 130 

Berson   75 

Berson  and  Silring .' 44,     45 

Besnier 120 

Bevel  Gears    322 

Bicycle  Analogies    39 

Bienvenu   127 

Biplane,  Analogy  with  Box  Kite. 169 

Biplanes    169 

Birch    376,  392 

Black,  Dr 67 

Blade  Outlines  for  Propellers 246 

Blanchard,  Jean-Pierre   72,  88,  120,  234,  442 

Bleriot,  Alighting  Gear 370 

Bleriot  Machines,  History  of 135 

Bleriot,  Louis    30,  31,  119,  135,  153,  167,  168,  217,  241,  260,  281,  423 

Bleriot  Machines   207,  259,  312,  358,  396,  439,  440 

Block  Chains   316 

Boat  Convoys    38 

Boat  Paper 393 

Body-Cradle  Control 229 

Boilers,  Steam   301 

Bolts    391 

Borelli   120 

Bourcart    120 

Box  Kite,  Invention  of 123 

Box  Tails    220 

Boxwood     376-392 

Braided  Linen    393 

Brass 392 

Brasses  and  Bronzes    386 

Brazing    391 

Breakdown   Not    Inability 34 

Brcant    120 


INDEX— Continued  497 

Ereary,  F.  W. 233 

Breguet 125 

Breguet  Helicopter-Aeroplane    130 

British  Aeronautical  Exhibition 299 

Bronze,  Aluminum    386 

Bronze,   Phosphor    386 

Bronzes  and  Brasses 386 

Burners    303 

Burners,  Acetylene    415 

C 

Cable  Chains  317,  310 

Calcium,  Carbide * 413 

Calcium  Light  416 

California  Spruces  379,  392 

California  Vulture  159,  356 

Carbon  Steel  382 

Castings  .- 382 

Cast  Iron 384,  393 

Castor  Oil  353 

Casualty  Appraised  by  Horror  Rather  Than  by  Statistics 30 

Carbureters  291 

Catgut  389,  393 

Cavallo,  Tiberius 67 

Cavendish  67,  98 

Cayley  120 

Cedar  392 

Cements  and  Glues  390 

Center  of  Gravity,  Beneath  Center  of  Pressure  with  Correct  Surfaces  at 

Correct  Angles  213 

Center  of  Pressure  184,  213 

Center  of  Pressure,  Forward  Inclination  of 190 

Chains  and  Sprockets 314 

Chains,  Block  316 

Chains,  Cable  317,  319 

Chains,  Crossed  315 

Chains,  Lateral  Flexibility  in 316 

Chains,  Roller 317,  318 

Chains,  Silent  317 

Chains,  Standard  American  Roller 318 

Change-speed  Gear  314 

Chanute  Biplane 136 

Chanute,  Octave 22, 

120,  136,  139,  140,  141,  142,  150,  155,  169,  218,  363,  398,  404,  451 

Chanute  Patent  462 

Charles,  M 69,  71 

Chauviere  Propellers 24 1 

Cherry 392 

Chestnut  392 

China  Grass  390,  393 

Choinski,  Description  of  Wing  Warping  in  1881 217 

Chord  Angles  204 

Chromaluminum 385,  393 

Chrome-Nickel  Steel 383 


498  INDEX— Continued 


Chromium   383 

Chronometer    426 

Cleared  Areas,  Necessity  for  in  Starting  and  Alighting 366 

Clement-Bayard     83,  157 

Clips    391 

Close-to-Ground  Flight   30 

Clutches     325 

Cody  Biplane   219,  259,  260,  314,  315,  390 

Cody,  8.  F 154 

Coastal    Winds     59 

Coleoptera    (Wing-case    Insects) 166 

Colliex,  M 153 

Compass     422 

Compound  Movements  In  Controls 227 

Compressed  Air   309 

Compressed  Gas 109 

Condor    160 

Cone  Bearings 346 

Confined  and  Unconflned  Air  as  Vehicle  Support 29 

Conservation  of  Energy,  Relation  of  Law  of  to  Soaring  Flight 202 

Construction   and    Materials 372 

Continuous  Rotating  Mechanism  Unknown  in  Animal  Economy 26 

Contents,   Table   of 7 

Controlling  Means • 226 

Cooling,  Air   290 

Cooling,    Water    289 

Copper 393 

Cordage  and  Textiles   387 

Cornu    125 

Cornu  Helicopter 129 

Cost  of  Construction  and  Maintenance,  Low 28 

Cotton    388 

Crossed    Chains * 315 

Cups,  Grease   352 

Cups,  Oil    349 

Currents  and  Vortices    448 

Curtias,  Glenn  H 22,  31,  154,  155,  169,  241,  448 

Curtiss  Biplanes   209,  229,  259,  358,  370,  400 

Curvature  of  Wings 207 

Curved  Surfaces 172 

Curved-Wing  Aeroplanes    26 

Cushions,  Pneumatic 440 

Cylinder  of  Rotation  About  Wing 187 

Cylindrical  Roller  Bearings 340 

D 

Daedalus  and  Icarus 119 

Daimler  Motor    87 

Dandrieutv    120,  128 

Danger  of  Flight 32,  33 

Danjard    154 

Deal    380 

Defolco    143 

Degen    120 


DeLabouret 


INDEX—  Continued  499 

.................................   120 

12° 
Delagrange    ......................................................   153 

Dellwik-Fleischer  Process  for  Producing  Hydrogen  .....................     99 

DeLouvrie    .......  ................................................    12° 

Demountability    ...................................................   437 

Design  of  Aerial  Vehicles  ..........................................   443 

D'Esterno,  Count    .........................................  141,  146,  154 

D'Esterno's    Wing    Warping  .........................................   216 

Deutsch,  M  ......................................................      82 

Diameters,   Propeller      .............................................   250 

Dihedral   Angle    ..................................................  21JJ 

Dihedral  Angle,  Objection  to  ........................................   207 

Dihedral  Angles  of  Wings  ................  ..........................   207 

Dirigibles,  Effect  of  Size  Upon  ...................................... 

Dirigibles,  Non-rigid    ..............................................     89 

Dirigibles,  Rigid     .................................................      89 

Dirigibles,  Semi-rigid    .............................................      89 

Distance  and  Speed  ................................................   420 

Drag  Ropes  ......................................................   HO 

Drift     ...................................  .....................  210,  211 

Dropped  Weights   .......................................  •  .........   362 

Drums,   Winding    .................................................   363 

E 

Edison   .......................................................  125,  128 

Efficiencies  of  Aerial  Propellers  .....................................  253 

Efficient  Modern  Aeroplanes  ........................................  434 

Elastic  Bodies,  Lack  of  Knowledge  Concerning  Laws  of  Motion  of  .......  195 

Electric  Lamps     ..................................................  411 

Electric  Lighting    .................................................  411 

Electric  Motors     ..................................................  304 

Electric  Welding     .................................................  391 

Elevators    ........................................................  224 

Elm    .........................................................  376,  392 

Empire  de  I'  Air,  L'  ................................................  156 

Enamels    .........................................................  389 

Energy,  Question  of  Amount  Required  for  Flight  ......................  192 

Engine,  Antoinette    ...............................................  280 

Engine,  Anzani     ..............................................  280,  281 

Engine,  Fiat    .....................................................  280 

Engine    Muffling    .................................................  296 

Engine,  Naphtha   .................................................  309 

Engine,  Renault     .................................................  280 

Engine,  R.   K.   P  ..................................................  281 

Engines,  Gasoline    ................................................  277 

Engines,  Multicylinder  Gasoline    ....................................  277 

Engines,  Revolving  Cylinder    .......................................  282 

Engines,  Steam    ..................................................  299 

Engines,  V-shaped   ...........................  ,  ....................  280 

English  Channel,  First  Crossed  by  Balloon  ...........................  72 

Escape  Valves  for  Balloons   .............................  ...........  107 

Equilibrium,  Automatic    ...........................................  221 

Exchange  of  Momenta  ...........................................  *  .  195 


500  INDEX— Continued 

Exploration  and  Prospecting 34 

Express  and  Mail. 433 

F 

Fabrics    388 

Facing  Wind  in  Starting  and  Alighting 367 

Factors  of  Safety 30 

Fan  Blowers  and  Windmills 237 

Farcot  Machine   124 

Far-man,   Henry    30,  153,  154,  169,  209,  221,  228,  241,  446,  474 

Farman  Biplanes 259,  358,  371,  404 

Feathering  Paddles  for  Propulsion 232 

Ferber,    Captain   Ferdinand 140,  155 

Ferber  Biplane   208 

Fiat  Engine   280 

Fir,   (New  England  Spruce) 392 

Fir,   (Norway    Spruce) 329 

First  Commercial  Applications  of  Flight 33 

Fish,  Flying   161 

Flag,   Waving  of 179 

Flapping  Flight 159 

Flat  Surfaces   171 

Flexible   Roller  Bearings 340 

Flexible  Rudders   224 

Flight,    Flapping 159 

Flight  of  Wing-case   Insects 159 

Flight  Records   473 

Flight,  Soaring    159 

Flights,  Tabular  History  of . 476 

Floats   359,  370 

Fluids,  Impact  of  Elastic 198 

Fluid  Movements,  Nature  of 175 

Fluids,  Rotations  in 1 79 

Flying  Animals  and  Aeroplanes 162 

Flying  Animals,   Size  of 159 

Flying  Dragon     163 

Flying  Fish     161 

Flying  Frog    161 

Flying  High     446 

Flying  Lemur 163 

Flying  Low    447 

Flying  Machines  Cheaper  Than  Motorcycles 29 

Flying  Squirrels    163 

Flywheels 297 

Folding  Wings   438 

Force  and  Motion   193 

Forced  Lubrication   350 

Forms  of  Propeller  Surfaces 244 

Forms  of  Surfaces 169 

Framing  of  Aeroplanes 230 

Franklin,  Benjamin 70 

Freedom  of  Travel    40 

French  Walnut   378 

Frost 120 


INDEX— Continued  501 

Fuel   Injection   293 

Fuel   Pumps 294 

Fuels    303 

Fuselage 439 

G 

Gain  of  Weights  over  Areas 27 

Garnerin,  Andre  Jaques 442 

Gas,   Compressed    109 

Gas,  Cost  of 79 

Gas,     Leakage   of 79 

Gasoline  Engines 277 

Gasproofi ng  Balloon  Fabrics 95 

Oauchot    147 

Gear,   Bleriot  Alighting 370 

Gears,   Alighting    369 

Gears  and  Shafts   320 

Gears,  Bevel 322 

Gears,  Spur  321 

Generators,  Acetylene 414 

Gibson 120 

Gerard    120 

Giffard,  Henri   80 

Glaisher  and  Coxwell 44,  56,  74 

Glider,   The  Montgomery 173 

Gliding  Flight,  Indefinite 231 

Glue    393 

Glues  and  Cements 390 

Gcdard,  Louis 84 

Gores  for  Balloons 75 

Grade  Indicator   425 

Graphite    344 

Gravity  Lubrication    349 

Grease  Cups   352 

Green 120 

Gross     75 

Gross  Dirigibles    83,  84 

Gut,  Silkworm    390 

Gutta  Percha   95 

Gyroscope    222 

Gyroscopic  Action  of  Propellers 262 

H 

Hair    390 

Hammer,  William  J 450 

"Hangars"     . 115 

Hardwoods    374 

Hargrave  Clockwork  Motors 123 

Hargrave,  Laurence    22,  122,  124,  155,  235,  236,  299 

Hargrave   Models    235 

Hargrave  Rubber-band  Motors. 123 

Hargrave    Steam   Engine 122 

Head  Resistance,  Effect  of  Rear  Form  Upon 215 


502  INDEX— Continued 

Head  Resistance,  Lower  to  Unit  Area  of  Small  Surfaces 315 

Head  Resistances     210 

Head  Resistance,  Effect  of  Projected  Area  Upon 213 

Head  Resistance,  "Wind-cutting"  Shapes  of  Little  Value  in  Reducing 213 

Heating 441 

Heavier-than-air  Flying  Machines 117 

Heights  Attained  With  Balloons 44 

Helicopter    25,  125 

Helicopter-Aeroplane    126,  130 

Helicopter,  Analogy    With    Aeroplane 131 

Helicopter,  Berliner    129 

Helicopter,  Cornu 129 

Helicopter  History    125 

Helicopter  Toys     127,  128 

Helicopters  in  Nature 126 

Helicopters,  Lateral  Progression  of 130 

Helium     102 

Hemlock    377,  392 

Hemp    393 

Henson   22,  155 

Hero    127 

Herring,  A.  M 22,  136,  155 

Hickory 377,  392 

Hinged  Wing  Tips 217 

Holly 378,  392 

Hopkins    71 

Horizontal  Rudders    224,  225 

Horn    393 

Hot-tube  Ignition   287 

Housing    440 

Human  Hair    393 

Hydroplane    316,  359 

I 

Icarus    119 

Ignition  by  Heat  of  Compression , 287 

Ignition,  Hot-tube 287 

Ignition,  Jump-spark    285 

Ignition,  Make-and-Break    284 

Illuminating  Gases    101 

Impact  of  Elastic  Bodies,  Formula  of 196 

Impulse,   Starting    360 

Incandescent  Lamps    412 

Incandescent  Mantles   416,  417 

Incidence,  Angle  of 204 

Inclined  Surfaces 364 

Indefinite  Gliding  Flight 231 

Indicator,  Grade    425 

Influence  of  Wind  on  Aerial  Travel 437 

Insect  Fliers 166 

Insect  Fliers,    Largest 167 

Internal   Balloons    Ill 

Iron    382 

Iron  (Commercial)  393 


INDEX— Continued  503 

Iron  (Pure    Wrought) _ 393 

Ivory    393 

J 

Japans    389 

Jay    120 

Jeffries 72 

Jets  and  Streams,  Phenomena  of , 182 

Jobert    120,  124 

Jump-spark  Ignition   285 

"June  Bug" 438,  439 

K 

Kaufman 120 

Keith   120 

Kerosene    355,  418 

Knabenshue    85 

Krupps 383 

L 

Lacquers    389 

Lambert,  Count  de 474 

Lamboley     120 

Lamp,  Nernst   413 

Lamps,  Arc 411 

Lamps,  Electric    411 

Lamps,  Incandescent 412 

Lamps,  Oil    411,  417 

Lamps,  Tungsten     412 

Lana,  Francis    , 67,  102 

Lancewood 392 

Langley  Machines     207,  208,  260,  381,  404 

Langley,  Professor    23,  136,  275,  300,  359,  369 

Langley's  Law   212 

Larch    392 

Large  Craft,  Not  Much  Use  for 27 

Large  Surfaces,  Reason  for  Greater  Sustention  Per  Unit  of  Area 184 

Lateral  Dimensions  of  Machines   206 

Lateral  Progression  of  Helicopters 130 

Latham    31,  119,  396 

Launching  Aeroplanes  Over  Water   38 

Launching  Prom  Height   368 

Launching  Vehicles     365 

Launoy  and  Bienvenu 127 

Law  of  Areas,  Bulks,  and  Weights 27 

Laws  of  Aerodynamics 170 

Leather    393 

Letaudy  Brothers    82 

Lebatidy  Dirigibles    83 

LeBris,  Captain   120,  146,  155,  216 

Lift  and  Drift 210,  211 

Lendenfeld    235 


504  INDEX— Continued 

Level 425 

Lever  Controls   228 

Levavasaeur,   M 155 

"Liberte,"    French    Dirigible 83 

Light,  Calcium    416 

Llghter-than-air   Machines 24,  25,  65 

Lighting,  Electric    411 

Lighting  Systems 410 

Lights,  Arrangement  of 419 

Lignum  Vitse    392 

Lilienthals     140,  147,  149,  151,   169,  172,  190,  218,  364,  404,  405,  451 

Lilienthal,  Oustav   137 

Lilienthal,  Otto    137 

Lilienthal   Patent    463 

Lilienthal's  Tables 211 

Limitations  Expected 35 

Linen 388 

Linfleld    155 

Link   Belts 317 

Linseed  Oil 95,  389 

Liquid  Air 50,  309 

Locust 392 

Lome,  Duptty  de 80 

Longitudinal  Balance   220 

Lorraine-Dietrich    Motor    85 

Louvers 442 

Loup,  Michael    156 

Low    Flying    447 

Lubricants    352 

Lubrication     347 

Lubrication,  Forced 350 

Lubrication,  Gravity     349 

Lubrication,  Splash 347 

Luminous  Paints    449 

M 

MeCurdy    22 

Magnalium    385,  393 

Mahogany     378 

Mahogany  (Honduras) 392 

Mahogany  ( Spanish)     392 

Mail  and  Express   433 

Make-and-break  Ignition    . . . , 284 

Maloney,  Daniel   138,  143,  144,  146 

Maloney,   Death   of 145 

Manila 393 

Mantles,  Incandescent   416,  417 

Maple    378,  392 

M arey   120,  235 

Masses  in  Motion    194 

Materials  and  Construction 372 

Materials,  Strength  of 399 

Maxim    (Multiplane)     260,  404,  405 

Maxim,  Hiram  8 22,  128,  156,  258,  300,  358 


INDEX— Continued  505 

Meerwein     120 

Mercurial  Barometers 424 

Metals    381 

Meteorelogy     53 

Mineral  Oils 352 

Miscellaneous  Controls   229 

Miscellaneous  Propelling  Devices    231 

Mobility  of  Air    03 

Modification  of  End  Sections 189 

Moisture  on  Balloon  Surfaces 112 

Monoplanes,  Greater  Sustention  of 167 

Montgolflera    68,  97,  127 

Montgolfiers,  First  Experiment  of 68 

Montgomery  Aeroplane 406 

Montgomery,  Flights  in  1905 138,  139 

Montgomery   Glider    173,  407 

Montgomery,  John  J.,  Prof 22, 

31,  138,  140,  141,  142,  146,  167,   168,  173,  181,   217,  221,  275,  368,  451 

Montgomery  Paper  Presented  at  Aeronautical  Congress  of  1893 174 

Montgomery  Patent 457 

Moore 120 

"Motor"  Account  of  Montgomery  Flights 139 

Motor,  Anzani    398 

Motor  Standardization   28 

Motors,  Antoinette    85 

Motors,  Daimler     87 

Motors,  Electric     304 

Motors,  Lorraine-Deitrich 85 

Motors,  Spring    , 310 

Motors,  Vapor    309 

Mouillard,  Louis  Pierre 141,  146,  156,  216,  451 

Mouillard  Patent   462 

Moy,  Thomas    156 

Muffling  Engines    296 

Multicylinder   Gasoline   Engines 277 

Multiplanes 168 

Murrell    120 

Muslins  for  Balloon  Envelopes  93 

Multibladed  Propellers   248 

N 

Nails 390 

Naphtha  Engine 309 

Napier    120 

Nature's  Mechanisms    25 

Navigation,    Aerial    446 

Nernst  Lamp    413 

Nettings,    Balloon 103 

Newcomb,  Simon   160 

News  Service   434 

Nickel-Aluminum    385,  393 

Nickel     383 

Non-lifting  Balloons 107 

Normal  Resistance  of  Surfaces ».,....,.., 211 


506  INDEX— Continued 

"Normally-Flat"  Surfaces  of  Wright  Patent 455 

Normand,  M,  Le 442 

Norway  and  California  Spruces 379 

Norway    Spruces 379 

O 

Oak 378 

Oak,  English    392 

Oak.  Live    392 

Oak,  White    392 

Oil    389 

Oil,  Castor    353 

Oil  Cups    349 

Oil  Lamps    411,  417 

Oil,  Linseed    389 

Oil,  Olive    353 

Oil,  Sperm     354,  417 

Oilers,  Ring  and  Chain 348 

Oils,  Animal     354 

Oils,  Mineral 352 

Oils,  Vegetable    353 

Olive  Oil   353 

Open  Balloon  Necks 110 

Oregon  Pine 392 

Ornithopter    25,  118 

Ornithopter  History   118 

Orthogonal  Flight  120 

Osculatory  Circles  of  Parabola 181 

Osier    380 

Oxygen  and  Acetylene 416 

P 

Paint,  Aluminum   388 

Paints  and  Varnishes 388 

Paints,   Luminous    440 

Palmer 120 

Panhard    Motors    280,  289 

Parabola,  Correct  Section  for  Sustaining  Surfaces 180 

Parabola,  Osculatory  Circles  of 181 

Parabola,  Relations  of  Focal  Lengths  to  Chord  Lengths 191 

Parabola,  Study  of 181 

Parabolic  Sections  in  Propellers 245 

Parabolic  Surfaces    173 

Parabolic  Surfaces,   Compound  Effects  of 183 

Parabolic  Surfaces,  Reflection  of  Impulses  Beneath 182 

Paraboloid  Reflectors   419 

Parachutes    442 

Parseval    Dirigibles    83,     84 

Partinium    385,  393 

Passenger  Accommodation  439 

Patent,  Chanute    462 

Patent,  Lilienthal 463 

Patent,  Montgomery     457 

Patent,  Mouillard    462 

Patent,  Wright    451 

Patents   , 451 


INDEX— Continued  507 

Pearwood    392 

Pedal   Controls 229 

Pelterie,  Robert  Esnault 154,  167,  228,  258,  259,  408 

Penaud,    A 120,  124,  127,  146,  147 

Percales  for  Balloon  Envelopes .  93 

Peripheral  Speeds  of  Propellers 250 

Pettigrew    120 

Phillips,  Horatio   157,  168,  173 

Phillips,  W.  H.... 127 

Phosphor    Bronze    386 

Pichancourt 120,  124 

Pilcher,  Percy  8 22,  147,  218,  404,  407 

Pines    379 

Pine,  Pitch 392 

Pine,  Red    392 

Pine,  White    392 

Pine,  Yellow     392 

Pivoted  Rudders    224 

Placing  of  Propellers 258 

Plain  Bearings 342 

Plane  Placed  at  Angle  to  Stream 179 

Plumwood   392 

Plural   Carrying   Surfaces 221 

Plural  Propellers    259 

Plural  Wing  Tips    220 

Plurality  of  Operators   227 

Pneumatic  Cushions   440 

Poplar     379,  392 

Power  Plants   273 

Practical  Utility 39 

Pressure  Above  Surfaces   187 

Priestly 68 

Prigent    120 

Progress  Against   Wind    27 

"Progress  in  Flying  Machines,"  Book 120,  121 

"Progress  in  Flying  Machines,"  Account  of  Early  Montgomery  Work  in..  142 

Projected  Area,  Effect  Upon  Head  Resistances 213 

Propeller  Analogies 237 

Propeller-Blade    Arrangements 252 

Propeller-Blade   Outlines    246 

Propeller   Blocks    267 

Propeller  Diameters    250 

Propeller-driving   Arrangements    313 

Propeller  Efficiencies 253 

Propeller,  Effective  Surface  of 241 

Propeller  Materials    264 

Propeller  Pitch  and  Blade  Angles 242 

Propeller  Placings    258 

Propeller  Surfaces,  Forms  of 244 

Propeller  Thrust     361 

Propeller,  Typical 270 

Propellers,  Gyroscopic  Action  of 262 

Propellers,  Multibladed    248 

Propellers,  Peripheral    Speeds  of 250 

Propellers,  Plural    , 250 


508  INDEX— Continued 

Propellers,  Single    259 

Propellers,  Two-bladed    249 

Propulsion     231 

Pterodactyl    160,  165 

Pulleys  and  Belts , 324 

Pumps,  Fuel    294 

Q 

Quartermain    120 

Questions  of  Safety 29 

Quinby    120 

R 

Radii  of  Action  436 

Radii  of  Action  Possible  to  Secure 27 

Rail    Launching    Devices 359 

Rapid  Transit,  Secret  of  All 28 

Rattan    105 

Rawhide     390,  393 

Reaction  Turbines   127 

Reciprocating-wing  Systems 25 

Reciprocating  Wings 234 

Records,   Flight    473 

Reflectors    418 

Reflectors,  Paraboloid 419 

Renard    82,  128 

Renault  Engine 280,  291 

R.   E.   P.   Engine 281 

R.  E.  P.  Monoplanes 31,  226,  358,  408,  440 

"Republlque,"  French  Dirigible   83,  84 

Resultants  Beneath  Surfaces 18 1 

Revolution  Counters   422 

Revolving-Cylinder  Engines   282 

Reversible  Sprockets   319 

Richet 120 

Ring  and  Chain  Oilers 348 

Rip  Cords   108 

Rittenhouse 71 

Rivets 391 

Robert 69,  71 

Rocket  Schemes  310 

Rocking   Wings    288 

Roller  Bearings 339 

Roller  Chains    317,  318 

Romaine,   M "2 

Rotating-wing   System    25 

Rotations  in  Fluids 179 

Rozier,  Pilatre  de 70 

Rozier,  Pilatre  de,  Death  of 72 

Rubber    95 

Rudders,    Flexible 224 

Rudders,   Front    220 

Rudders,  Horizontal 224,  225 


INDEX— Continued  509 

Rudders,  Pivoted • 224 

Rudders,   Rear 220 

Rudders,    Twisting 225 

Rudders,   Vertical    224 

Runners    • 360,  370 

S 

Saint-Fond,  M.  Faujns  de 69 

Saint  Victor,  Castillion  de    74 

Santos-Dumont,  Alberto 82,  104,  140,  148,  229,  261,  408 

Santos-Dumont  Machines    .208,  358 

Shaeck 74 

"Scientific  American,"  Account  of  Montgomery  Flights 139 

"Scientific  American  Supplement,"  Description  of  Wing-warping  in  1881. .  217 

Scraping  Plain  Bearings 345 

Screw  Propellers   236 

Screws   391 

Shafts 320 

Shoulder-Fork  Control 229 

Seats    440 

Sections  of  Sustaining  Surfaces 171 

Selfridge,  Lieutenant 259 

Semi-Parabola 180 

Servero,  Auguste    104,  107 

Shafts  and  Gears 320 

Shellac    389 

Shifting  Weight 218,  221 

Siemens,   Electric   Motor 81 

Signals 449 

Silent  Chains  317 

Silk 388,  393 

Silk  Cord    390 

Silkworm  Gut .390,  393 

Single  Propellers   259 

Size  of  Flying  Animals 159 

Sizes  of  Machines 27 

Skin  Friction   210 

Skin  Friction  of  Propellers 257 

Slip  in  Propellers    243,  244 

Small-unit  Vehicle  Ideal 28 

Smeaton's  Tables 211 

Smyth    120 

Soaring  Bats 165 

Soaring   Birds    164 

Soaring,  Explanation  of 200 

Soaring  Flight 159 

Soaring  in  Calm  Air 274 

Soaring,   Phenomena  of 192 

Sockets,  Strut 386,  387 

Softwoods 379 

Soldering    392 

Sounding  Balloons    44 

Spar  Varnish 389 

Speed  and  Distance .;.......... 420 


510  INDEX— Continued 

Speed  and  Flying  Radius   26 

Speed,  Effect  Upon  Sustention 212 

Speed  of  Aerial  Travel 27 

Speed  of  Reciprocation  With  Wings 235 

Speeds,  Maximum  and  Average 27 

Speeds  of  Land  Travel 38 

Speeds  Ultimately  to  be  Attained 26 

Spencer    83 

Sperm  Oil 354,  417 

Splash  Lubrication   347 

Split  Bamboo  375 

Sport    432 

Spring  Motors   310 

Sprockets  and  Chains 314 

Sprockets,   Reversible    319 

Spruce     379,  392 

Spruces,  Norway  and  California 379 

Spur-gear  Drives   321 

Spur  Gears 321 

Squirrels,  Flying   163 

Standard  American  Roller  Chains 318 

Starting  and   A.     bting 356 

Starting  Devices   357 

Starting  Impulse  360 

Steam  Boilers    301 

Steam  Engines 299 

Steam  Engines,  Hargrave    122 

Steel     382 

Steel,   Cast   393 

Steel,   Malleable   Castings    393 

Steel,  Common  Piano  Wire 393 

Steel,  Tinned  Piano  Wire 393 

Steel  Alloy   383 

Steel,  Carbon  382 

Steel,    Chrome-Nickel    383 

Steering    Aeroplanes     223 

Steering  Balloons    113 

Steering  Balloons  by  Drag  Ropes 114 

Steering,  Effect  of  Propellers  on 262 

Btevene    85 

Straight  Pitch  in  Propellers   241 

Strength  of  Materials    398 

StrtngfeUow    22,   157,  299 

Structure,  Always  a  Visible  and  Invisible 214 

Strut   Sockets    386,  387 

Btnive  and  Teleachiff 120 

Surface  Moving  a  Fluid 178 

Surface,  "Normal"  Resistance  of 211 

Surfaces,  Arrangement  of   205 

Surfaces,  Circular  Arcs 172 

Surfaces,  Design  of  Tandem 191 

Surfaces,  Forms  of 169 

Surfaces,    Inclined    364 

Surfaces,  Parabolic  173 

Surfaces,  Pressure  Above 187 


INDEX— Continued  511 

Surfaces,  Proper  Form  and  Adjustment 180 

Surfaces,  Staggered 205 

Surfaces,   Superposed 205 

Surfaces  Sustaining,  Values  of  Different 210 

SUring    75 

Sustaining  Force,  Forward  Inclination  of 211 

Sustaining  Surfaces  as  Continuous  Wings 206 

Sustaining   Surfaces  as   Separate   Wings 200 

Sustaining  Surfaces,  Sections  of 171 

Sustention,  Effect  of  Adjacent  Surfaces  Upon 212 

Sustention,  Effect  of  Change  of  Outline  Upon 212 

Sustention,  Increase  With  Speed 212 

Sutton    .120 

Swinging  Wing  Tips 219 

Sycamore 392 

T 

Table  of  Contents 7 

Tables   of  Wind   Pressures 214 

Tables,  Lilienthal's   211 

Tables,   Smeaton's    211 

Tabular  Comparison  of  Flying  Animals  and  Aeroplanes 162 

Tabular  History  of  Flights 480 

Tails,    Box    220 

Tallow     354 

Tandem   Propellers    263 

Tandem    Surfaces    191 

Tangential    190,  211 

Tanks     310 

Tapered  Roller  Bearings    341 

Tatin,  Victor 120,  157 

Teak     392 

Technique  of  Aerial  Navigation   41 

Temperature,  Effects  of  on  Balloons 112 

Terminology,    Aeronautical    464 

Terms,  Aeronautical    464 

Terrestrial  Adjuncts   449 

Textiles  and  Cordage   387 

Thermopile    307 

Things  Possible  but  not  Profitable 20 

Three  Traverslble  Media   . . .  < 24 

Thrust  Propeller   361 

Tilting  Wing  Tips 217 

Tissandier,  Oaston  and  Albert 81,  305,  307 

Toy  Helicopters 127,  128 

Trade   Winds    60 

Transaquatic  Mail  Lines 38 

Transmission    Elements    313 

Transportation  Never  Unlimitedly  Flexible   35 

Triplanes 

TrouvG    121,  124 

Trouve"  Electric  Motor   305 

Tungsten 383 

Tungsten  Lamps   412 


512  INDEX— Continued 

Turnbuckles 386,  387 

Twisting  Rudders ; 225 

Two-Bladed  Propellers 249 

Types  to  Survive 24 

Typical  Aeroplanes   394 

Typical  Propellers 270 

U 

United  States  Weather  Bureau 450 

Uranium 383 

V 

Vacuum  Balloons    67 

Valves,  Balloon   107 

Vanadium    383 

Vanes,  Wind 425 

Vaniman,   Melvin    84 

Vaniman  Triplane  169 

Vapor    Motors 309 

Variable  Wing  Areas   218 

Varnishes  and  Paints 388 

Vaseline     352 

Vaulx,  Henry  de  La 74 

Vegetable  Oils 353 

Vehicles,   Applications  of  Aerial 428 

Veneers  and  Bendings 380 

"Venetian-blind"    Constructions    168 

Vertical    Rudders    224 

Vertical  Surfaces  for  Balancing 216 

Vertical  Surfaces  in  Nature's  Fliers 163 

Vertical  Surfaces,  Rare  in  Nature 209 

Victoria  Aluminum   385 

"Ville  de  Nancy,"   French  Dirigible 83 

Vinci,  Leonardo  da 120,  126 

Visible  and  Invisible  Structure  of  Machine 214 

Voisin  and  Curtiss  Machines 227 

Voisin-Farman  Triplane  169 

Voisin,  Gabriel   31,  123,  140,  153,  169,  221 

Voisin  Biplanes 154,  209,  321,  358,  367,  409 

Vortices  and  Currents    448 

V-Shaped  Engines   280 

Vuia 157 

Vulcanized  Fiber   344 

Vulture  of  California,  Largest  Soaring  Bird 159 

W 

Walnut 378 

Walnut   Black 392 

Walnut   Hickory    392 

Walnut   French    378 

Warfare     429 

Water  Cooling  289 


INDEX— Continued  513 

Ware  Lines  in  Fluids 178 

Wave  Surfaces  for  Propulsion 233 

Weights,   Dropped    302 

Weiss     221 

Welding,    Antogenous 391 

Welding,    Electric    391 

Wellman,    Walter    84 

Wenham,  F.  II 22,  168 

Wenham,  F.  H.,  First  Suggestion  of  Multiplane 149 

Whalebone     393 

Wheel   Controls    228 

Wheeler     120 

Wilcox,  James   71 

WWiie     143,  144 

Willow    380,  392 

Winding  Drums   363 

Windmills   and   Fan    Blowers 237 

Wind  Pressures,  Tables  of 214 

Wind  Vanes    425 

Wind  Velocities   62 

Wing  Outlines    204 

Wing  Surfaces   189 

Wing  Surfaces,  Modification  of  End  Sections 203 

Wing  Tips,  Hinged 217 

Wing   Tips,    Plural 220 

Wing  Tips,   Swinging 219 

Wing  Tips,  Tilting 217 

Wing  Warping,  Early  Use  of 216,  217 

Wing   Warping   for   Balancing 216 

Wings,    Continuous    206 

Wings,  Dikedral  Angle  of 207 

Wings,    Folding    438 

Wings,   Lateral   Curvature  of 207 

Wings,   Reciprocating    234 

Wings,  Separate ' 206 

Wings,  Speed  of  Reciprocation  with 235 

Wire    281,  386 

Wire  Tightener    387 

Wise,  John   74 

Wolframinium    385,  386 

Wolframinium,  in  Zeppelin  Dirigible 87 

Wood    105,  373 

Wright    254,  289 

Wright  Brothers,  Wilbur  and  Orville 149,  425,  451 

Wright  Machines.. 209,  227,  259,  260,  262,  275,  280,  312,  314,  315,  359,  361, 

362,  388,  399,  409,  474 

Wright  Machines,  Vertical  Surfaces  in  Elevator  of 210 

Wright  Machines,   Wings  Drooped  in 207 

Wright,    Orville    152,  259 

Wright   Patent    152,  451 

Wright  Patent,  "Normally  Flat"  Surfaces  of 455 

Wrights.  .22,  30,  140,  150,  169,  190,  217,  218,  224,  228,  229,  360,  364,  365,  371 

Wright  Starting  Device 362 

Wright,  Wilbur 152,  261 


514  INDEX— Continued 

Y 

Yam  a  da,  laaburo   84 

Yew    392 


Zeppelin    85,  386 

Zeppelin  Dirigibles 86,   88,  90 

Zeppelin    Envelope   Material 92 


YD  07532 


Engineering; 
Library 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


YD  07532 


Engineering 
Library 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


